The warning follows arrests abroad of suspected Islamic militants and the leak of an FBI report that said between five and 15 operations were planned on cities worldwide. London is considered one of the cities that could be targeted, although senior British police officers and the security services have indicated that there is no evidence of a terrorist plot.
Deputy Assistant Commissioner Alan Fry, head of the anti-terrorist branch at Scotland Yard, yesterday urged people to be alert. He said: "There may be groups or individuals who may try to disrupt the celebrations and people should be on their guard against any suspect packages or anyone acting suspiciously.
"Recent arrests in Jordan and the United States have heightened the public's awareness of a possible threat from Islamic extremist groups, he said. "The public are our eyes and ears and we would encourage them in the run-up to Christmas and the millennium to be vigilant and to contact police if they notice anything suspicious."
Doubts have been expressed that London is likely to be a target because it is used by Islamic organisations as a base. There will be a huge police operation for the millennium celebrations, with leave cancelled for all Metropolitan police officers.
Last month, police sources revealed that Britain was on its highest state of alert since the Omagh bomb because of a threat from dissident Irish republican groups.
The authorities in the United States believe that terrorists linked to the Saudi dissident Osama bin Laden may try to create havoc around New Year. Washington has also issued a warning to all Americans overseas because of possible attacks.
Fourteen members of an extremist group were arrested in Jordan last week on suspicion of plotting to attack American targets and tourist sites there during the millennium celebrations.
Jordan is seeking the extradition from Britain of Omar Abu Omar, an alleged sponsor of the group, who this week denied that he was involved with them. He also denied he was linked to Mr bin Laden, who has declared war on Americans and is wanted for last year's bombing of the US embassies in Kenya and Tanzania, which killed 224 people. He arrived in Britain in 1993 as a political refugee and said he had been teaching Islamic theology.
Last year, a Jordanian court sentenced him in absentia to life in prison for a series of explosions, including one in the car park of an Amman hotel.
An Algerian was also arrested last week in the state of Washington after allegedly taking a car full of explosives from Canada to the US. The man had reservations to fly from Seattle to New York then to London, where he was thought likely to be meeting contacts of an Islamic terrorist group.Reuse content