Dissident IRA groups have targeted the Conservative party conference this fall in Birmingham according to a leading Tory politician. The conference will beheld in October.

In 1984, the IRA almost killed Margaret Thatcher at a similar conference in Brighton.

Patrick Mercer, ex-chairman of the Commons subcommittee on counter-terrorism said that dissidents are seeking to stage a spectacular.

He said: "They want to kill by the end of August in order to get themselves poised for whatever operations they can mount in September leading up to the Tory party conference in early October. There are doubts over whether they have the capability, but the aspiration is certainly there and West Midlands police would be crazy not to take the threat seriously."

Owen Paterson, the Northern Ireland secretary, said the government was monitoring the situation, and stated there was now "unprecedented co-ordination between different security forces.

"We have made a substantial number of arrests and we are bearing down on them," he said. "But we do not underestimate the threat they represent."

Laurence Robertson, the Conservative chairman of the Northern Ireland affairs select committee, stated the news was "extremely worrying".

"So far it has been contained to the province but whether it is there or on the mainland it is very worrying. We hope it is not yet another chapter but it could be and it has to be dealt with."

Over the past 18 months dissidents have raised their profile in an attempt to undermine the peace process.