KUALA LUMPUR -- The United States, Britain and Australia closed some diplomatic missions in Asia Wednesday in response to security threats on the anniversary of the September 11 terror attacks on New York and Washington.

The public was refused access to U.S. embassies and consulates in Indonesia, Malaysia, Vietnam, Cambodia and Pakistan, while Britain closed its missions in Jakarta, Singapore and Phnom Penh.

Australia did the same in Dili in East Timor and Singapore.

U.S. Ambassador to Indonesia Ralph Boyce said Osama bin Laden's terror network Al-Qaeda was linked to a "specific" threat that forced the indefinite closure to the public of U.S. diplomatic missions there.

British ambassadors in Jakarta and Phnom Penh said last minute decisions to shut their embassies were "precautionary", but gave no further details.

A ***New York Times*** report from Jakarta quoted American officials as saying that investigators had uncovered a plot by the radical Islamic Organization Jemaah Islamiyah, which has links to Al-Qaeda, to attack several American embassies in Southeast asia.

Australian Foreign Minister Alexander Downer said Canberra closed its embassy in Dili in East Timor, formerly part of Indonesia, because of the same threats which forced the closure of U.S. embassies in Southeast asia. And in Washington U.S. Attorney General John Ashcroft warned that "most intelligence focuses on potential attacks on us interests overseas." "Information indicates that Al-Qaeda cells have been established in several south asian countries in order to conduct car bombs and other attacks on U.S. facilities."

In Afghanistan, focus of the U.S.-led war on terrorism in the wake of the September 11 attacks last year, a gunman opened fire on the allies' Bagram Air Base north of the capital Kabul.

No one was injured and a man was detained for questioning, said a U.S. military spokeswoman.

In Southeast Asia, the U.S. Embassy in Manila was one of the few which remained open, but scores of elite policemen armed with high-powered assault rifles guarded the facility.

-------------------------------------------------- ---- additional policemen were also deployed at the israeli and british embassies as well as airports, seaports and vital installations, philippine officials said.

that sort of security bristled at potential terrorist targets across asia, from the world's tallest twin towers in malaysia to airports and dockyards as memories of a year-old tragedy half a world away evoked fears of new attacks.

at the petronas twin towers in malaysia's capital kuala lumpur, which stand higher than those destroyed in new york and were the target of a bomb threat a year ago, hundreds of people failed to turn up for work.

with the us navy warning shippers of unconfirmed reports that al-qaeda had planned attacks against oil tankers, a police spokeswoman in hong kong said security had been increased at the harbour as well as at the international airport.

in japan, a us military spokesman in okinawa, home to two-thirds of 47,000 us troops stationed in the country, declined to comment on the security status at bases, citing security reasons. a us embassy spokesman in tokyo said: "we are taking appropriate measures all the time."

the us embassy in cambodia was closed for "security reasons" after cancelling a commemorative service to be held in memory of the more than 3,000 people who died in the us attacks.

a memorial service did go ahead in singapore, but amid strict security.

there were no visible extra security measures in beijing, where much of the embassy district is already under tight guard to ward off further incursions into foreign missions by north korean refugees seeking asylum.

the us embassy in bangkok remained open for business as usual but security had been beefed up, an embassy official said.