While there is no information to suggest that American citizens or their property in Malaysia are under any threat, they are advised to remain alert and vigilant, said the US Embassy today.

"American citizens are urged to maintain a high level of vigilance and to take appropriate steps to reduce their vulnerability, such as maintaining a low profile, varying routes and times for all required travel, and treating mail and packages from unfamiliar sources with suspicion," a US Embassy spokesperson said.

An advisory, which was released in wake of suspected terrorist attacks on World Trade Center in New York and the Pentagon in Washington DC, advised US citizens to register with the embassy.

Yesterday, Inspector General of Police Norian Mai announced that security around the US Embassy's compound in Kuala Lumpur would be increased to prevent any 'untoward incidents'.

The attacks involved two commercial airliners which smashed into the 110-storey World Trade Center's twin towers at 8.45am and 9.03am (Malaysian time 8.45pm and 9.03pm) yesterday, causing both structures to collapse into rubbles.

The US Department of Defense, or Pentagon, was also hit by another airplane which damaged a section of its sprawling facilities, while a fourth airliner crashed with in the eastern sea board state of Pennsylvania.

Both the World Trade Center and Pentagon are considered symbols of the US' superpower in the global economy and military respectively.

Casualties are expected to be in the thousands, and US president George W Bush has promised to bring the perpetrators to justice. However, to date no group has claimed responsibility.

The horrific attacks, which prompted the New York Stock Exchange to close down yesterday, are expected to cause severe economic reverberations all over the world.

Attacks condemned

Meanwhile, two local non-governmental organisations today strongly condemned the attacks, calling it an 'insane act of terrorism'.

"The barbaric act has wreaked havoc and chaos that is unspeakable; the immensity of the horror and loss on tens and thousand of innocent lives are unimaginable," said Aliran president P Ramakrishnan.

He added that such acts of terrorism and fanaticism cannot be condoned under whatever circumstances and for whatever reasons.

Malaysian Youth Association president Stephen Doss also expressed sorrow over the tragedy.

"What is certain is that we must always be on our guard against threats, whether real or unrealised," Doss said.

"We pray that the world will be spared from future senseless deaths such as these. There can be no sensible excuse that anyone can give for the death of these innocent civilians," Doss said.