Britain’s Prime Minister David Cameron walking out of 10 Downing Street in London, yesterday. Photo: Paul Hackett/Reuters

Prime Minister David Cameron asked lawmakers to consider whether Britain should join US-led air strikes against Islamic State militants in Syria, but his spokeswoman said he had not yet decided whether to push for a parliamentary vote on the issue.

Britain conducts regular attacks in neighbouring Iraq and flies drones over Syria to gather intelligence. But unlike some other coalition partners it does not target Islamic State positions in Syria as Cameron failed to get the go-ahead from Parliament to do that in 2013.

The death of 30 Britons in an Islamist attack in Tunisia last week has changed the calculus, prompting Cameron, via his spokeswoman, to ask lawmakers to start thinking about whether they would back wider action.

“What has changed is the growing evidence that IS [Islamic State] poses a threat to people here in Britain and our national security,” Cameron’s spokeswoman told reporters yesterday.

“And in that context the Prime Minister does think that MPs [lawmakers[ should be thinking about these issues. His view is that there has been and continues to be a case for doing more in Syria.”

Cameron, who was visibly shaken after losing the 2013 Syria vote, wants to be sure he can win any vote in Parliament this time and so is not expected to call a vote until after the summer so he can gauge the support of the opposition Labour Party which is in the throes of choosing a new leader.

The question would need to be “properly and carefully deliberated” before Cameron decided whether or not to call a vote, his spokeswoman said.

“He thinks it would be better if there was consensus for such action,” she added.

Cameron himself believed there was a legal case to take such action, she said, adding that Britain was already flying drones and planes over Syria to gather intelligence that could be used in any future strikes.

“We have assets that are flying over both Iraq and Syria,” said the spokeswoman, saying Islamic State had lost 25 percent of its territory since the coalition began air strikes in Iraq.

She rejected the idea that such strikes in Syria could strengthen President Bashar al-Assad, who Cameron has in the past said is part of the problem not the solution.

Meanwhile, British police said yesterday they had charged a woman with being a member of Islamic State and inciting terrorism on social media, and in a separate case had arrested a 15-year-old girl on suspicion of a terrorism offence.

The woman, 26, from Burton upon Trent in central England who cannot be named for legal reasons, was arrested by counter-terrorism officers at London’s Heathrow Airport in February after arriving on a flight from Turkey.

West Midlands Police said she had been charged with publishing messages on Twitter in October last year which encouraged people to commit or prepare acts of terrorism, and being a member of the banned organisation Islamic State (IS).

Separately, London police said they had arrested a 15-year-old girl in east London on suspicion of preparing acts of terrorism. She is currently in custody awaiting questioning.

Some 700 Britons are estimated by the authorities to have travelled to Syria or Iraq, many to join IS.