PHNOM PENH, Cambodia — The U.S. Embassy in Cambodia has issued a security alert over an alleged plot to set off a bomb during the country's traditional New Year holiday, which runs from Thursday through Monday.

The alert advises U.S. personnel to exercise caution around Wat Phnom, a temple in Phnom Penh said by Cambodian officials and media to be the target of a plot by the Khmer National Liberation Front, an overseas anti-government group.

Prime Minister Hun Sen on Tuesday publicly warned of the alleged plot, saying strengthened security measures would ensure safety. He has repeatedly charged before a general election in July that his political opponents seek to cause unrest, in what is generally seen as an effort to disrupt their ability to organize and function freely.

The alert was posted on the embassy's website and social media outlets. "Exercise caution in areas with large crowds. If you see an unattended object, leave the area immediately. Monitor local media for updates. Be aware of your surroundings," it said.

Embassies for the U.S. and other Western nations tend to err on the side of caution in issuing such warnings.

Cambodia's Interior Ministry and a pro-government newspaper released details of the alleged plot. They said the northwestern town of Siem Reap, the site of the famous Angkor temple complex, was also an alleged target.

Hun Sen's government has used a combination of threats, accusations of conspiracies and legal action to attack his opponents. Almost all critical news media have been shut down and the opposition political party has been banned. The courts are widely regarded as being under the influence of Hun Sen's ruling Cambodian People's Party.

Hun Sen has held power for more than three decades and declared his intention to remain for at least two more five-year terms.

The website of the independent Phnom Penh Post newspaper quoted Sam Serey, the Denmark-based head of the Khmer National Liberation Front, as denying the alleged bomb plot.