Lord Butler claimed on Thursday that it would have been "improper" for his inquiry team to have written a report that brought down Tony Blair.

The former Cabinet secretary told MPs on the public administration committee that it was for parliament and the electorate to decide whether a prime minister should remain in office.

"If we had come across evidence of distortion or wilful negligence, we would not have hesitated to identify that and those concerned with it," he said.

"On the political issues, we wanted to give people the information but we felt that really the proper place where governments should survive or fall is with parliament and the electorate.

"It would have been a heavy responsibility and one where it would have been improper for us to say that we think the government should resign on this issue."

Tony Wright, the Labour chairman of the committee, told Lord Butler that many felt his report had "dodged the question of responsibility".