Supporters of Muammar Gaddafi may attempt to carry out a terrorist attack on UK soil in revenge for military action in Libya, senior government sources have warned.

The security services have told ministers that a number of conversations between British-based Libyans suggesting support for a revenge attack have been intercepted recently. The intelligence, which was passed to Nato allies, was recorded shortly before the start of the no-fly zone operation.

The discussions about how to support Colonel Gaddafi were held by expatriates who retain close links with their homeland, the Italian newspaper Corriere della Sera reported. One man, who was under surveillance by MI5, is reported to have been recorded saying: "We must fight, we must be dedicated to give support." The intelligence cited in the warning was deemed "reliable" by MI5, the newspaper reported.