Cameron says will call Putin to explain Sharm bomb fears

London - Prime Minister David Cameron said he would call Russian President Vladimir Putin on Thursday to explain Britain's concern about the "strong possibility" that a bomb may have brought down a Russian jet over the Sinai last week.

"I'll be calling President Putin in a moment or two to discuss this with him," he told reporters, adding that he would "explain to him why we've taken the action we've taken" by suspending passenger flights to and from Sharm el-Sheikh.

"If that Russian airliner was brought down by a terrorist bomb, that does have very real implications," he said, adding: "Because it's a strong possibility, it's right to act".

"We need to see the results of that investigation. The reason we've acted before that is because of intelligence and information that we've had that gave us the concern that it was more likely than not a terrorist bomb."

Cameron said 20,000 British holidaymakers would be repatriated from Sharm el-Sheikh and explained that British airlines would be flying empty planes to the Red Sea resort to bring them back.

"We're working round the clock with the Egyptians to put in place the necessary security measures at the airport," he said ahead of a meeting in Downing Street with Egyptian President Abdel Fattah al-Sisi.

"We want to start as soon as possible. There are a relatively simple and straightforward set of things that need to happen at Sharm el-Sheikh airport to give us greater certainty of safety at that airport," he added.

Some 224 people, most of them Russian tourists, were killed when the plane bound for Saint Petersburg plummeted to the ground 23 minutes after taking off from Sharm el-Sheikh on Saturday.