The UK has not concluded that Israel is committing genocide in Gaza, nor that any of the British-made parts for F-35 jets sold to Israel have directly led to breaches of international humanitarian law, ministers have told parliament.

Ministers have also rejected calls for an independent audit of UK arms sales, but admitted they were not in a position to say if Israel’s assault in Gaza had led to any breaches of humanitarian law owing to the complexity of the fighting terrain.

They rejected a proposal that the crime and policing bill for England and Wales be amended to make it easier to prosecute foreign nationals in the UK courts suspected of war crimes, including deprivation of aid or the killing of aid workers, a change that would make it easier for Israeli government leaders to be arrested if they visited the UK.

Israel’s president, Isaac Herzog, is due to visit London on Wednesday, where he will give an address and visit No 10.