A worldwide net was closing in on suicide hijacking prime suspect Osama bin Laden last night - as his Taliban protectors appeared to accept he could have been behind the attacks.

The Afghan regime postponed a decision on whether to hand him over to the US after global diplomatic moves gathered pace and there was news of a ceasefire between Palestinians and Israel because of the crisis.

Prime Minister Tony Blair was last night preparing to embark on a hectic round of shuttle diplomacy in a bid to galvanise support - crisscrossing the Atlantic with meetings in Berlin, Paris, New York, Washington and Brussels planned for the next three days.

Thousands of Afghans continued to attempt to flee their country amid fear of reprisal strikes as other Taliban voices promised a Jihad, or holy war, if Afghanistan was targeted by western forces.

The latest moves in the anti-terrorist war came as the first British relatives of victims of the World Trade Centre attacks arrived in New York, exactly a week after the outrages.

First signs of a crack in support for bin Laden from the hard-line Taliban regime came when its information officer was quoted as accepting the man wanted by Washington "dead or alive" may have been behind the hijackings, despite his categorical denials.

But reports from the regime were confused with no certainty over when a meeting of clerics in Kabul to decide bin Laden's fate would take place, after being expected yesterday.

According to the official Bakhtar News Agency, deputy Taliban leader Mullah Mohammed Hasan Akhund urged the people to prepare for a Jihad against America.

Many Pakistanis living along the 1,500-mile border with Afghanistan promised to join the Jihad against America, and possibly their own government, if there are retaliatory strikes.

"America is putting a gun on Pakistan's shoulder to fire at Afghanistan. The Pakistani people cannot accept this," said Haji Abdul Razzaq, a mechanic in Peshawar, near the border.

Jet fighters patrolled the skies over Peshawar yesterday as the Taliban pointed Scud missiles at the city and nearby tribesmen deployed their own considerable arsenals to fight alongside them.

Yesterday, 3,000 people in Karachi demonstrated, warning of more attacks.

"Until now, only one World Trade Centre has been destroyed," demonstrators shouted in unison in English. "But we will destroy all of America. We will die for Taliban. We will die for Islam. We will die for Osama."

As the international coalition to smash terrorism was being forged, Defence Secretary Geoff Hoon confirmed that Britain had to beware of chemical or biological weapon attacks from rogue groups.

"It's certainly something that we have to guard against," Mr Hoon told BBC Radio 4.

"I believe that the appalling events of last week have certainly caused us to think afresh about the preventive actions we need to take."

But Mr Hoon stressed there were already contingency plans to deal with such attacks.

In the Middle East, Palestinian leader Yasser Arafat ordered a unilateral ceasefire and told his forces to prevent any firing on Israelis and hold back even if fired upon.

Israel immediately responded by promising not to launch attacks on Palestinians. It also said it would withdraw tanks from Palestinian areas it had seized in recent days and dozens of tanks were seen pulling back from the outskirts of the West Bank town of Jenin.

l A suspected hijacker in the US terror strikes met an Iraqi intelligence official earlier this year, it was reported last night. Mohamed Atta, one of the men the FBI believes hijacked the American Airlines plane which hit the north tower of the World Trade Centre, met the official somewhere in Europe, CNN reported.

US Attorney General John Ashcroft refused to confirm or deny the report.

But President Bush has said that any state involvement with the terrorist group responsible would lead to retaliatory measures by the US.