The US has urged its citizens to leave Saudi Arabia

The United States has warned of possible terrorist attacks throughout East Africa and parts of south-east Asia following the triple suicide bombing in Saudi Arabia.

At least 34 people died in the attacks in Riyadh, which the US and Saudi Governments have blamed on Osama Bin Laden's al-Qaeda network.

The US state department has recommended that Americans defer non-essential travel to Kenya and to carefully review plans to visit East Africa in general.

The alert came as the Lebanese Army said that - with help from Syrian forces - it had arrested members of group that planned to attack an unidentified Western embassy in Lebanon.

Last week Lebanese officials said the army had smashed a terror network planning to kill the US ambassador, arresting members of a fundamentalist group based in a Palestinian refugee camp.

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Correspondents say Syria's latest involvement is significant because it comes at a time when both it and Lebanon are under pressure from the US to aid peace-making in the Middle East and clamp down on radical groups.

Meanwhile, the Kenyan authorities have issued a photograph and details of a suspect alleged to be linked to a plot against British and American interests in the country.

The suspect, Fazul Abdullah Mohammed, is described as the chief architect of last November's bombing of a hotel near Mombasa which killed 15 people. He is also wanted by the FBI over the 1998 bombing of the US embassies in Kenya and Tanzania.

On the same day as the Mombasa bomb, there was an unsuccessful attempt to shoot down an Israeli charter plane as it left Mombasa.

In a strongly-worded warning, the US state department said the Kenyan Government "might not be able to prevent" further attacks.

"The US Government has received indications of terrorist threats in the region aimed at American and Western interests, including civil aviation," the warning said.

Malaysia warning

The state department also warned of a "continuing concern" of attacks against Americans in Malaysia, particularly in the state of Sabah.

It was a renewal of a warning issued after the October blasts which killed more than 200 people on the Indonesian holiday island of Bali.

The Bali nightclub bombings targeted western tourists

The warning specified the threat posed by the Jemaah Islamiah, a militant south-east Asian network, and by Abu Sayyaf guerrillas based in the neighbouring southern Philippines. Both groups have been linked to al-Qaeda.

The new warnings came as Saudi Arabia faced criticism from the US that it did too little to prevent Monday's suicide bombs that devastated three expatriate housing complexes.

"Saudi Arabia must deal with the fact it has terrorists inside its own country," said White House spokesman Ari Fleischer.

"Their presence is as much a threat to Saudi Arabia as it is to Americans."

'Intense pressure'

Western and Saudi officials have warned of the danger of more attacks.

The US State department said there was a "potential of further terrorist attacks", while the British Foreign Office described the threat as "high".

The BBC's security correspondent Frank Gardner says Saudi authorities are coming under intense pressure to confront the threat from al-Qaeda more effectively.

The US has sent a team of FBI agents to gather evidence alongside Saudi police, while the UK has sent two specialist teams to Riyadh to help with the investigation.

The US has urged all US citizens to leave Saudi Arabia immediately, while the UK has authorised its non-essential diplomats in the kingdom to return home if they want to.

The UK embassy in Riyadh has confirmed two Britons were among 11 Westerners - mainly Americans - killed in the blasts.

Victims also included seven Saudis and several Jordanians, while the nine suspected attackers, who shot their way past armed guards and rammed vehicles packed with explosives into the compounds, also died.