US, Israel issue Sri Lanka attack alert after 'terrorist' threat against tourists

LONDON -- The U.S. Embassy in Colombo, Sri Lanka, issued a warning to citizens late on Tuesday based on "credible information" warning of an attack in the southeast of the country.

The embassy said in a post on its website that the threat was related to "popular tourist locations in the Arugam Bay area," an area of famous and well-visited beaches known for its surfing.

"Due to the serious risk posed by this threat, the embassy imposed a travel restriction on embassy personnel for Arugam Bay effective immediately and until further notice," the embassy wrote.

U.S. citizens, it added, "are strongly urged to avoid the Arugam Bay area until further notice."

The embassy did not offer any more information about the nature or source of the threat.

The notice urged citizens to report all suspicious activity to local authorities, keep a cell phone or other form of communication close by and monitor local media for updates.

Israel's National Security Headquarters also asked Israelis to immediately leave the Arugam Bay area and the coastal region in the south and west of Sri Lanka, citing "a terrorist threat."

It advised Israelis in affected areas -- including the cities of Ahangama, Galle, Hikkaduwa and Weligama -- to leave the country or relocate to the capital Colombo citing a higher level presence of local security forces there.

"Israelis planning to come to the country are advised to postpone their trip unless it is an essential trip," the warning said.

Those already present in Sri Lanka should "avoid externalizing Israeli identity symbols in the public sphere, including avoiding movement with Hebrew shirts or symbols that betray origin and religion," the NSH said.

Israelis should also avoid gatherings at sites where there is no security, it said.

The State Department lists Sri Lanka as a "Level 2" nation in its risk advisory guide, meaning Americans there should "exercise increased caution."

The State Department's latest advisory for Sri Lanka was issued on Oct. 2 and noted that protests relating to the "economic and political situation in Sri Lanka can erupt at any time."

"In some instances, police have used water cannons and tear gas to disperse protesters," it added. "U.S. citizens are reminded to avoid all gatherings, even peaceful ones, that could turn violent with little or no warning."

"Terrorist attacks have occurred in Sri Lanka, with little or no warning," it added, targets having included tourist hotspots, transportation hubs, shopping areas, government facilities and entertainment venues, among others.

"The U.S. government has limited ability to provide emergency services to U.S. citizens in remote areas," the advisory said.

This is a developing story. Please check back for updates.

ABC News' Jordana Miller contributed to this report.