Dissident republicans could be planning a significant bomb attack in the run-up to the British general election, anti-terrorist police warned yesterday.
Scotland Yard believes the threat from the "Real IRA" represents a "graver danger" than the car bomb that exploded outside the BBC's headquarters in London in March.
The Metropolitan Police yesterday started its second advertising campaign in six months asking people to be vigilant.
With less than two weeks until the election, the Assistant Commissioner of Specialist Operations at Scotland Yard, Mr David Veness, said intelligence gathered on the threat from dissident republicans gave reason "to fear present terrorist intentions to attack the election process". "One looks in sheer horror at the impact of Omagh with all the death and tragedy that it caused - that remains the most significant challenge that this particular grouping represents," he said.
British police believe the dissidents are securing weapons from "readily available` sources in Eastern Europe and could be switching their tactics away from targeting road and rail networks to "nationally symbolic" targets, such as the Royal Mail and the BBC.
"There is a trend around nationally symbolic significant targeting, but that can be very broad-ranging," Mr Veness explained.
There are also some indications that a dissident cell has been operating in London. Mr Veness said:
"We have people who appear to know their way around London, which suggests that one or more may have resided in London.
But of course timed devices would have given them the opportunity to leave these shores. I have to keep an open mind about it."
The number of republican attacks in Britain increased during the 1992 and 1997 election campaigns and there have been six dissident republican incidents in London in the past year.
Mr Veness also pointed out that there had been 10 dissident republican bombing incidents in Northern Ireland so far this year, already matching last year's total.
Six radio stations in London will run advertisements from today until the end of the election campaign asking people to report any suspicious packages and calling on landlords and car dealers to note any unusual transactions.