New fears of terrorism swept parts of Asia today when security guards were posted at Sydney's Opera House and Australia and Canada shut down their embassies in Manila, citing specific threats of attacks by Muslim extremists, possibly within days.

Both governments strongly warned their citizens to stay away from the Philippines, long wracked by violence by militant groups linked to Osama bin Laden's al Qaeda network.

In Manila, armed police closed streets, set up barricades and circled the Australian Embassy.

Australian Foreign Minister Alexander Downer said Canberra had received a "very specific" intelligence report Wednesday night that warned of a possible Islamic militant attack.

"It is not only location-specific, targeting the Australian Embassy itself, but also it's time-specific in the sense that we are talking over the next few days," Downer told Australian Broadcasting Corp. radio.

Downer said threats had also been made against targets linked to other nations, which he declined to identify.

The minister said 24-hour security by private guards had been put in place to protect some national landmarks. They included Sydney's Opera House and Harbor Bridge, Australia's two top tourist attractions, and the Melbourne Cricket Ground, one of its largest stadiums.

He described the move as a precaution and not related to a specific threat.

Today, Canada also closed its embassy in Manila "for an indefinite period of time," according to a recorded message on the embassy telephone line.

"We have recently received specific and credible information of a threat to the Canadian Embassy in Manila and we're advising Canadians not to travel to the Philippines until further notice," Canadian Foreign Affairs spokeswoman Marie-Christine Lilkoff said.

Both Canada and Australia have supported Washington's war on terrorism.

Australia has been on a heightened alert since Oct. 12, when bombs shook the Indonesian resort island of Bali, killing about 190 people, half of them Australian tourists.

The U.S. Embassy in Manila was closed today for the Thanksgiving holiday, but officials planned to open as usual on Friday, spokeswoman Karen Kelley said.