LONDON, Sept 16 The head of Britain's domestic spy agency has warned that the UK faces potent new threats from terrorism incubated in Northern Ireland, the Middle East and North Africa.

Jonathan Evans, director-general of MI5, said in a rare public speech late on Thursday that attacks on the UK were increasingly likely to emanate from Somalia, Yemen or Belfast, as Al Qaeda-linked groups were fleeing strongholds in Pakistan.

The spy chief said the 2012 London Olympic Games would likely be a major target for terrorist attacks, and warned that dissidents who rejected Northern Ireland's peace process could strike mainland British cities for the first time since 2001.

Mr Evans said Irish republican splinter groups had access to weapons, including Semtex explosives, and funds from smuggling and drug trafficking.

“We cannot exclude the possibility that they might seek to extend their attacks to Great Britain, as violent republican groups have traditionally done,” Mr Evans said, making a speech late on Thursday to security industry professionals in central London.

While security officials have improved defences against the threat from extremism, Mr Evans said Al Qaeda plots against Britain were “uncovered on a fairly regular basis,” with officers dealing with a handful of different cases at any one time.

But he said the number of plots against Britain with links to Pakistan's tribal areas had dropped from three-quarters to about a half, mainly as a result of drone strikes against Al Qaeda leaders - but also because of a sharp increase in activity in the Middle East and North Africa.

Would-be terrorists from around the world, including dozens of people either born or living in Britain, are training in camps in Somalia run by the Al Qaeda-aligned terrorist group Al Shabaab, Mr Evans said.

He warned that Somalia shared “many of the characteristics that made Afghanistan so dangerous as a seedbed for terrorism”.

“I am concerned that it is only a matter of time before we see terrorism on our streets inspired by those who are today fighting alongside Al Shabaab,” he said.

On the threat from Northern Ireland, Mr Evans said his agency had hoped dissident violence would recede following the establishment of the province's joint Catholic-Protestant government under the 1998 peace accord.

“On the contrary we have seen a persistent rise in terrorist activity and ambition in Northern Ireland,” he said.

Mr Evans said dissidents had mounted or attempted 30 attacks this year in Northern Ireland - including a car bombing at MI5's base in the region, which caused no serious injuries - an increase from 20 attacks last year.

Republican dissidents last made a successful attack in England in August 2001, exploding a car bomb near a shopping centre in west London, injuring 11 people.

However, Mr Evans said the priority for his 3,500 staff remains the threat from Al Qaeda and affiliated groups -and securing the 2012 Olympics.

“The eyes of the world will be on London during the Olympic period and the run-up to it. We have to assume that those eyes will include some malign ones that will see an opportunity to gain notoriety and to inflict damage on the UK and on some other participating nations,” Mr Evans said.

He said his agency also was concerned about the threat from devotees of Anwar Al Awlaki, the US-Yemeni citizen who had become Al Qaeda's leading English-speaking voice.

“There is a real risk that one of his (Awlaki's) adherents will ... mount an attack in the UK, possibly acting alone and with little formal training,” Mr Evans said.

Also of concern are terrorists now returning to their communities after serving jail terms, he said.

The spy chief also said the discovery of 10 deep-cover Russian agents in the United States in the summer proved that traditional espionage had not ended with the Cold War.—AP