UK faces potent new threats from terrorism with 2012 London Olympic Games likely to be a major target of al-Qaeda bombers, the country's top intelligence official has warned.
Jonathan Evans, director-general of Mi5 - Britain's domestic intelligence service, said threats were emanating from Northern Ireland, Middle East and North Africa, as al-Qaeda linked groups are moving out of Pakistan.
The spy chief said London Olympics were under major threat from dissidents, who reject Northern Ireland peace process as also homegrown Britons who had undergone trainings in camps run by al-Qaeda liked al-Shabab in Somalia.
In a wide-ranging address to Worshipful Company of Security Professionals in the City last night, Evans highlighted that "al-Qaeda threat has diversified - with new centres of extremism emerging in Somalia and Yemen - and the potential that terrorists could target the 2012 London Olympics."
While asserting that British security set up had taken measures to improve defences against the threat from Islamic extremists, the Mi5 chief said al-Qaeda linked plots were "being uncovered on regular basis" with officers keeping themselves abreast of intelligence inputs.
On the threat from Northern Ireland, he said there had been recently a sharp rise in terrorist activities and ambitions in Northern Ireland.
Evans said Irish republican splinter groups had access to weapons, including Semtex explosives, and funds from smuggling and drug trafficking and could strike mainland British cities for the first time since 2001.
But he said that number of plots against Britain with links to Pakistan's tribal areas had dropped by half mainly because of drone strikes which had degraded the capabilities of al-Qaeda and other foreign militants holed up there.
He cautioned that it was "nonsensical" to believe the terrorist threat could be "abolished" and any incident which did occur was the result of a "culpable government failure".
His warning comes after one group, the Real IRA, publicly threatened to target banks and other financial institutions in London, accusing them of "financing Britain's colonial and capitalist system".
Evans said while Mi5's "main effort" remained focused on international terrorism, it has been necessary to reinforce its presence in Northern Ireland to deal with the threat.
Since the start of the year there have been more than 30 attacks or attempted attacks on national security targets by dissident republicans, compared with just over 20 for the whole of last year, he said.
