Foreign Secretary Philip Hammond has said there is growing "momentum" among MPs in support of extending RAF air strikes against Islamic State into Syria.

Mr Hammond said ministers would give MPs the chance to reflect over the weekend on David Cameron's case for further action against IS - also referred to as Isil - before deciding whether to press for a Commons vote.

Despite the turmoil in the Labour Party over the issue, he indicated there was increasing confidence among ministers that parliamentary opinion is moving in their direction in the wake of the Paris terror attacks.

"I think there is a momentum," Mr Hammond told the Press Association during a visit to Tunisia where 30 Britons were killed in June in a gun attack on the resort of Sousse which was claimed by IS.

"There is a sense that we're filling in the gaps, we're answering the outstanding questions, and an increasing sense of a comprehensive approach to Syria."

He added: "The Prime Minister has set out his strategy. He's taken on board the concerns that people have expressed over the last months about military intervention in Syria, in particular the question of how we will finish the job against Isil, because we all know that air strikes alone will not destroy the organisation.

"He set out the answers to those challenges, and I think now, over the weekend, we'll allow Members of Parliament on all sides to go back to their constituencies, talk to their constituents, take the pulse of public opinion, and then let's see how things stand next week."

While the uncertainty over which way Labour MPs will vote has complicated the calculations over the parliamentary arithmetic, Mr Hammond reiterated that Mr Cameron would not go to the Commons unless he was sure of winning.

"To put this issue to the vote and lose would be to hand a propaganda coup to Isil, and we're not going to do that," he said.