Russia's shift in tone followed assertions by British and American officials that terrorism was likely the cause of the plane crash on the Metrojet Flight 9268, which exploded shortly after it took off from the Egyptian resort city of Sharm el-Sheikh.

All 224 passengers and crew were killed when the plane crashed in Sinai on the way to St Petersburg, Russia. on October 31.

Egypt and Russia have yet to formally announce the cause of the disaster and both countries have strongly dismissed claims that a bomb was responsible.

But communications intercepted by US intelligence agencies now suggest Russia believes the plane could have been downed by an explosive.

Within days of the crash, US and British Government sources suggested that intercepted communications chatter indicated that the plane had been brought down by an explosive device.

A US Government source said that neither Russia nor Egypt has accepted an offer from the FBI to assist them in investigating the crash.

FBI spokesman Joshua Campbell said they had offered "forensic assistance" and other unspecified services to both Russia and Egypt.

E/S1