A senior British officer today described how he urged Tony Blair to delay the invasion of Iraq two days before the start of conflict because preparations for dealing with the aftermath were not in place.

Major General Tim Cross – who was attached to the Office for Reconstruction and Humanitarian Assistance (Orha) set up by the US to manage the aftermath – told the official inquiry into the conflict that the preparations were "woefully thin".

In a statement, he said that he had briefed Blair in No 10 on 18 March 2003 about the shortcomings that they were facing.

"We talked for about 30 minutes or so. I was as honest about the positions as I could be, essentially briefing that I did not believe postwar planning was anywhere near ready," he said.

"I told him that there was no clarity on what was going to be needed after the military phase of the operation, nor who would provide it.

"Although I was confident that we would secure a military victory, I offered my view that we should not begin that campaign until we had a much more coherent postwar plan."

He also criticised the then-international development secretary, Clare Short – who subsequently resigned over the war – saying she would not allow one of her officials to work with him on a full-time basis because of her "well known concerns".

"This was, I am bound to say, unhelpful for me, and it was an early indicator that Whitehall was not much more joined up than Washington," he said.

"There was a strong reluctance to formally support Orha. We did have Dfid [Department for International Development] representation, but it was nowhere near sufficient to meet our needs," he said.

"Considering the expected scale of the humanitarian suffering, the projected numbers of [refugees], civilian casualties etc this was, once again, more than a little disappointing."