Jack Lemley, who controversially resigned as chair of the Olympic Delivery Authority (ODA) a fortnight ago, has cited political wrangling and escalating costs as the reasons for his decision.

Lemley, 71, who was only a year into a four-year contract, said at the time of the announcement that he wanted to return to the US to help with major bids his international construction and project management company was preparing.

However, in an interview with Idaho Statesman newspaper, Lemley said that political conflict and rising costs were major problems facing the project.

"I went there to build things, not to sit and talk about it," Lemley said, "so I felt it best to leave the post and come home."

The ongoing indecision over whether the Olympic stadium will house athletics or football after the Games was a major problem. "A football field is not compatible with an athletics stadium," he said.

Conflict with local businesses over relocation were a frustration, he said: "Some of the people were happy to move and some of them weren't. In any event, there was a huge amount of local politics. Those are the kind of things that confuse the process."

It is widely believed that the cost of the overall work – which includes one of the largest urban regeneration projects in Europe – will be in excess of the original budget.

Lemley suggested that the costs of the Games are spiralling, so he left to avoid tarnishing his reputation of delivering projects on time and on budget. "I felt it was better to come home now than face that in five or six years," he added.

His comments will anger Olympic organisers, who offered public support, despite the disappointment of his premature resignation. At the time, ill health and problems with regular commuting between America and Britain were seen as key factors in his decision.