Labour's shadow cabinet has just met for the first time since David Cameron made his case for air strikes against Isis in Syria. A majority of members are prepared to support military action, according to those present, but Jeremy Corbyn is not. At the start of the hour and a half meeting, the Labour leader read out a prepared statement stating his unconditional opposition to air strikes. He was supported by shadow international development secretary Diane Abbott, who said that she would never vote to send the armed forces to war, shadow communities secretary Jon Trickett and Parliamentary Labour Party chair John Cryer (who added that he was prepared to back the shadow cabinet's collective view). Shadow chancellor John McDonnell did not speak but has previously stated his opposition to air strikes.

The remainder, however, either favour or are prepared to support military action. Following Corbyn's statement, shadow foreign secretary Hilary Benn spoke, arguing that the tests set by Labour's conference motion in September (such as UN backing) had been met and that Cameron had made a "compelling" case for air strikes. He emphasised, however, that far greater clarity was needed from the government over the claim that there were 70,000 non-extremist Syrian opposition fighters rea dy to combat Isis on the ground. Benn was supported by deputy leader Tom Watson, who reminded the shadow cabinet that he had rebelled over Libya in 2011 and spoke of the atrocities committed by Isis in Syria and elsewhere. He called for the party to reach a collective decision and emphasised that the conditions set by the conference resolution had been met.

Shadow justice secretary Charlie Falconer agreed with Benn's assessment and said there was a clear legal case for intervention. Shadow education secretary Lucy Powell said she would on balance vote for air strikes and argued strongly for the shadow cabinet to reach a collective view, rather than holding a free vote. Shadow culture secretary Michael Dugher backed military action and said the decision was a test of whether Labour was merely a protest movement or an opposition that aspires to be in government. Shadow business secretary Angela Eagle, shadow health secretary Heidi Alexander and shadow Northern Ireland secretary Vernon Coaker also argued for intervention.

In a parliamentary statement earlier today, Labour Lords leader Angela Smith signalled she was prepared to support military action, pointedly arguing that "The first duty of any government is the safety, the security and the wellbeing of its citizens. My party does not take an isolationist or non-interventionist position, and we have never been reluctant to use force when it has been deemed necessary."

Despite a majority being prepared to support air strikes, the party's collective position remains undecided. A Corbyn aide said afterwards that the shadow cabinet was "halfway through" the decision making process and that a final view would be reached on Monday after MPs returned from their constituencies. Whatever the outcome, Labour will be badly split. A collective decision in favour of action would divide the leader and the shadow chancellor from their team (though, in the era of "new politics", it is far from impossible that they could vote different ways). A decision against action would leave Corbyn at odds with most of his shadow cabinet. A free vote would avoid a split but in the view of many frontbenchers leave Labour "unfit for government". It is untenable, they argue, for the opposition to avoid a collective view on an issue as grave as military action.

With the SNP and the Liberal Democrats set to vote against air strikes, Labour's position is crucial. Having said that he will only act if he can achieve a "clear majority", Cameron may pull the vote if Corbyn whips his party against.

Update: After Hilary Benn publicly declared that there was a "compelling case" for military action, Jeremy Corbyn has written to all Labour MPs stating that he "cannot support" Cameron's "current proposal for air strikes in Syria". He said:

I do not believe that the PM today made a convincing case that extending UK bombing to Syria would meet that crucial test. Nor did it satisfactorily answer the questions raised by us and the Foreign Affairs Committee. In particular, the PM did not set out a coherent strategy, coordinated through the UN for the defeat of ISIS. Nor has he been able to explain what a credible and acceptable ground forces could retake and hold territory freed from ISIS control by an intensified air campaign. In my view, the PM has been unable to explain the contribution of additional UK bombing to a comprehensive negotiated political settlement of the Syrian civil war, or its likely impact on the threat of terrorist attacks in the UK. For these, and other reasons, I do not believe the PM's current proposal for air strikes in Syria will protect our security and therefore cannot support it.

Shadow cabinet members are outraged by Corbyn's letter, which was not mentioned at the meeting. One told me: "It means he's broken the agreement he had with the shadow cabinet on continuing to discuss our position on things like whipping. It is utterly dishonest." Another said: "It will be seen as an incredibly hostile act. He's made little attempt to engage with and convince colleagues." An MP told me: "The problem is that Jeremy continues to operate as an individual rather than as the leader of a collective. Dangerous and damaging."