NEW YORK — Terrorism charges were unsealed Friday in New York against a purported al-Qaida-linked leader in Africa accused of leading a January attack at a gas plant in Algeria that killed more than 35 hostages, including three Americans.

The charges against Mokhtar Belmokhtar were announced by federal law enforcement officials in Manhattan. They include conspiring to support al-Qaida, use a weapon of mass destruction, discharge a firearm and use and carry an explosive. Additional charges of conspiring to take hostages and discharging a firearm in furtherance of a crime of violence carry a maximum penalty of death.

Authorities also said a $5 million reward was being offered for information leading to the arrest of Belmokhtar, who's also been known as "the one-eyed sheik" since he lost an eye in combat. Belmokhtar left al-Qaida in the Islamic Maghreb, the North African offshoot of the terrorist group, then formed his own spinoff.

He is accused of participating in a Jan. 16 attack on a Western-owned gas processing facility in a remote part of eastern Algeria near the border with Libya.

After a four-day standoff, the Algerian army moved in and killed 29 attackers and captured three others. At least 37 hostages, including one Algerian worker, died in the battle. Three Americans and scores of Algerian and foreign nationals were killed.

Belmokhtar "unleashed a reign of terror years ago, in furtherance of his self-proclaimed goal of waging bloody jihad against the West," U.S. Attorney Preet Bharara said in a release. "His efforts culminated in a five-day siege that left dozens dead."

The court papers said Belmokhtar appeared in an online video the day after the siege ended, claiming responsibility for the attack on behalf of al-Qaida.

The charges "describe a fanatical jihadist leading an extremist vanguard of an extremist ideology," said George Venizelos, head of the FBI's New York office.

He added: "As alleged, he kidnapped diplomats, formed his own terrorist organization that pledged fealty to al-Qaida, and masterminded the murderous siege of a civilian plant in Algeria that resulted in the deaths of dozens of hostages, including three Americans."

Belmokhtar was designated a foreign terrorist by the U.S. Treasury Department in 2003. Prosecutors said he was a key leader of al-Qaida's efforts in North Africa starting in 2008 as he led attacks that resulted in the kidnapping and murder of numerous individuals.

Among the attacks, the government said, was the December 2008 kidnapping of two Western diplomats working in Niger as part of a United Nations mission. The victims were held for about four months before their release in Mali.

Prosecutors say Belmokhtar in a videotaped statement in December had called for fighting in Algeria and elsewhere to oppose Western influence. After the attack in Algeria, three hostage-takers interviewed by U.S. law enforcement officers acknowledged Belmokhtar was an "emir" in their al-Qaida group and said they had received military training in another country prior to carrying out the attack, the government said.