The deputy chair of a watchdog at the heart of controversial changes to the NHS in England is under fire after it emerged he was sacked from his old job.
Chris Mellor, a board member of Monitor, was fired as Northern Ireland Water chairman after an investigation into how contracts were awarded.
Lib Dem MP John Pugh has questioned whether someone with such a "colourful history" was suitable for a key role.
But Monitor said it had confidence in Mr Mellor's ability to do his job.
Last week, Prime Minister David Cameron placed Monitor at the centre of his plans to reform the NHS in England, giving it more power to regulate hospitals and health providers around the country.
Currently, the body only regulates foundation hospital trusts.
Mr Mellor was sacked last March by Northern Ireland Water, along with three other board members, after an independent report found there was a serious breakdown in governance - and doubts over more than 20 contracts worth around £8m.
Northern Ireland regional development minister Conor Murphy even warned the company might have been open to legal action over how contracts were awarded.
Mr Pugh, chairman of a committee of backbench Lib Dem MPs overseeing health policy, told BBC News: "There is a concern in the National Health Service that some people in Monitor don't have experience in the NHS.
"Part of that anxiety is not just the powers that they will have but who will have them.
"One of the board members having a colourful history is not going to provide an assurance to people in the NHS."
But a spokesman for Monitor said: "Mr Mellor is an experienced member of Monitor's board and we have confidence in him to perform his role as deputy chair."
Mr Mellor has been a member of Monitor's board for seven years and his term expires on 31 March 2012.