The political career of Ehud Olmert, the Israeli prime minister at the centre of a deepening corruption inquiry, was hanging by a thread on Wednesday after his most important coalition ally called on him to make way for a new leader.

Ehud Barak, the defence minister and leader of the Labour party, told a news conference that the prime minister could not “simultaneously run the government and deal with his own personal affair” and called on Mr Olmert to “detach” himself from office.