A Downing Street spokesperson said:
The Prime Minister called Russian President Vladimir Putin earlier today.
The Prime Minister reiterated his condolences over the loss of Russian life in the Sinai plane crash. He explained that, as more information had come to light, our concerns that the plane may have been brought down by an explosive device had increased. We had therefore taken the difficult decision to suspend flights into and out of Sharm el-Sheikh as a precautionary measure, while we sought urgent reinforcement of security measures at the airport. The safety of British citizens was our primary concern.
The Prime Minister and President Putin agreed we face a common threat from terrorism. The President expressed his thanks for the call and his understanding for our concern for the safety of British citizens. They agreed to keep in close touch as the investigation progressed.