Britain’s parliament looks set to vote in favour of joining the bombing campaign against Islamic State (IS) in Syria on Wednesday, paving the way for sorties by its planes to start within days.

Prime Minister David Cameron, who stepped up pressure for air strikes after last month’s Paris attacks, will lead the House of Commons into more than 10 hours of debate on joining the US-led international military action.

Ministers are confident that lawmakers will then vote “Yes”, meaning the first Royal Air Force (RAF) planes could be bombing targets in Syria by the end of the week.

Cameron insists military action is needed to prevent attacks like the ones that killed 130 people in Paris last month, while insisting it will be accompanied by a diplomatic push to resolve the crisis in Syria.

“I will be making the arguments and I hope as many members of parliament across all parties will support me as possible,” he said on the eve of the vote.

But many experts, lawmakers and members of the public remain sceptical, and several thousand anti-war protesters marched in central London on Saturday and Tuesday.

Military experts question how much difference Britain will make to the coalition against IS jihadists in Syria, adding the move may be more about Britain wanting to be seen to stand shoulder-to-shoulder with allies like France and the United States.

“It will not make a big operational difference,” Professor Malcolm Chalmers of military think-tank the Royal United Services Institute (RUSI) told AFP.

“It is important symbolically, useful operationally, but not transformative.”

Cameron “emotionally feels very strongly that he should support France in its time of need,” added Ben Barry of the International Institute for Strategic Studies think-tank.

Britain already has eight Tornado fighter jets plus an unknown number of drones involved in strikes on IS targets in Iraq, an operation it joined last year.

However, it currently only conducts surveillance and intelligence missions over Syria.

In a rare move, weekly Prime Minister’s Questions have been cancelled and the parliamentary diary cleared for an all-day debate on the Syria strikes, with a vote expected around 2200 GMT or even later.

The motion up for debate stresses that Britain will not deploy ground combat troops while noting that allies including France and the United States had requested British assistance.