TORONTO - Canada shut its embassy in Tehran on Friday, severed diplomatic relations and ordered Iranian diplomats to leave, accusing the Islamic Republic of being the most significant threat to world peace.

The surprise action reinforces the Conservative government's close ties with Tehran's arch foe Israel but also removes some of Washington's eyes and ears inside the Iranian capital.

It comes as Iran's talks with world powers over its nuclear program have stalled and Israel is weighing the option of a military strike to prevent it from developing atomic weapons. Iran insists its nuclear program is for peaceful objectives only.

The move also underscores the widening gaps between Western countries' attempts to isolate and punish Iran and Tehran's efforts to forge closer ties with energy-hungry Asian trading partners such as India and Pakistan to counter Western sanctions. Iran's recent push to bolster and redefine its links with Asia makes the break with Canada a less serious blow to Tehran than it would have been years ago.

Foreign Affairs Minister John Baird said that the Canadian embassy in Tehran will close immediately and Iranian diplomats in Canada have been given five days to leave.

A spokesman for Iran's foreign ministry, Ramin Mehmanparast, called Canada's decision "hasty and extreme" and said that Iran would soon respond, the semiofficial Fars news agency reported.

A note in Persian posted on the door of Iran's embassy in Ottawa read: "Because of the hostile decision by the government of Canada, the embassy of the Islamic Republic of Iran in Ottawa is closed and has no choice but to stop providing any consular services for its dear citizens."

Baird said Canada was officially designating Iran a state sponsor of terrorism and gave a long list of reasons for Canada's decision, including Tehran's support for Syria's embattled President Bashar Assad in that country's civil war.

"The Iranian regime is providing increasing military assistance to the Assad regime; it refuses to comply with U.N. resolutions pertaining to its nuclear program; it routinely threatens the existence of Israel and engages in racist anti-Semitic rhetoric and incitement to genocide," Baird said in a statement. "It is among the world's worst violators of human rights; and it shelters and materially supports terrorist groups."

Baird said he also was worried about the safety of diplomats in Tehran following attacks on the British embassy there.

Britain downgraded ties with Iran following an attack on its embassy in Tehran in November 2011, which it insists was sanctioned by the Islamic Republic's ruling elite. After the attack, Britain pulled all of its diplomats out of Iran and expelled Iranian diplomats from U.K. soil.

Most European countries maintain a diplomatic presence in Tehran despite increased tensions over European Union sanctions that block imports of Iranian oil. The Swiss represent diplomatic interests of the United States, which broke ties with Tehran after protesters stormed the U.S. Embassy in the chaotic months following the Islamic Revolution in 1979. Fifty-two Americans were held for 444 days.

Canada's break with Iran removes another channel for Washington to get first-hand diplomatic assessments of Iranian affairs. Canada and Britain had been main conduits of information for the U.S., which also maintains special Iranian monitoring offices in several locations including Dubai.

But Canadian relations with Iran have been strained since former Canadian Ambassador Ken Taylor helped rescue six Americans during the hostage crisis three decades ago. The countries resumed normal diplomatic relations with an exchange of ambassadors in 1996.

But relations soured again in 2003 after Zahra Kazemi, a freelance photographer with dual Canadian-Iranian citizenship, died in custody. Kazemi was arrested while taking photographs outside a Tehran prison in 2003.

Canada also has criticized Iran over the arrest of pioneering Canadian-Iranian blogger Hossein Derakshan, who helped develop the first Farsi language blogs and is considered one of the founders of Iran's social media community. Derakshan was detained in 2008 and sentenced to nearly 20 years in prison two years later.

Canada hasn't had a fully accredited ambassador in Tehran since Iran ordered Canada's ambassador, John Mundy, to leave the country in 2007 after trying unsuccessfully to come to an agreement on an exchange of ambassadors for some time.

Baird said the skeleton staff that was operating Canada's embassy has already fled the country.

"The Iranian regime has shown blatant disregard for the Vienna Convention and its guarantee of protection for diplomatic personnel," Baird told reporters in Vladivostok, Russia, on the sidelines of the 21-nation Asia-Pacific Economic Co-operation forum. "Under the circumstances, Canada can no longer maintain a diplomatic presence in Iran. Our diplomats serve Canada as civilians and their safety is our No. 1 priority."

He also told Canadians to avoid traveling to Iran and warned Canadians with dual citizenship that Iran doesn't recognize the principal of dual nationality.

All Iranian diplomats in Canada have now been declared "personae non gratae," Baird said.

An Iranian semiofficial news agency, Mehr, said the Canadian decision was "in accord with the U.S. hostile policy" against Iran and that it "served Zionists."

Israeli Prime Minister Benjamin Netanyahu issued a statement praising Canadian Prime Minister Stephen Harper for his "bold leadership," which he said sends a "strong message to Iran and the entire world."

Israel views a nuclear-armed Iran as an existential threat, citing frequent references by Iran's leaders for Israel's destruction, its development of missiles capable of striking the Jewish state, and Tehran's support for violent Islamic militant groups hostile to Israel in Gaza and Lebanon.

"The determination shown by Canada is very important in order for the Iranians to understand that they cannot continue with their race for nuclear weapons," Netanyahu said. "This practical step must serve as an example of morality and responsibility to the international community," he said.

Israeli leaders have hinted that they may soon attack Iran's nuclear sites if U.S.-led international diplomacy and sanctions fail to curb the nuclear program. World powers involved in stalled talks with Iran all hope to avoid an Israeli strike and the possibility of igniting a larger war. They also hope to avoid an Iran with nuclear weapons.

Iran's demands include recognition of its right for uranium enrichment — at the center of the nuclear standoff — and calls for the U.S. and European allies to ease the sanctions that have hit Iran's critical oil exports and left it blackballed from key international banking networks.

The U.S. and others worry Iran could use its enrichment labs to produce warhead-grade material. Iran insists it seeks to make nuclear fuel for energy and medical reactors only.

"We share Canada's concerns regarding Iran's behavior," U.S. State Department spokesman Patrick Ventrell said. He cited Iran's "military assistance to the Assad regime, failure to comply with U.N. resolutions pertaining to its nuclear program and continued violations of human rights."

"We want all countries to join us in isolating Iran," Ventrell added.

Baird also registered Canada's displeasure over Russia's continued support for the regime in Syria in a meeting with his Russian counterpart, Sergey Lavrov.

"I've already had a meeting with my Russian counterpart and I did so in no uncertain terms," Baird said.

Canada and other countries are upset that Russia and China has repeatedly used their veto powers in the U.N. Security Council to block actions that could have led to sanctions against Assad's regime.

Iran, Syria's key remaining ally in the Middle East, has backed Assad's government for years, and has kept up its strong support for the regime since the uprising began in March 2011. Syrian activists say at least 20,000 people have been killed in the conflict.

U.S. officials have said they believe Iranian flights of aid to Syria include weapons. Iran denies arming Assad's regime.

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Associated Press writers Nasser Karimi in Tehran, Brian Murphy in Dubai, United Arab Emirates, Ian Deitch in Jerusalem, Phil Couvrette in Ottawa, Bradley Klapper in Washington and Charmaine Noronha in Toronto contributed to this report.