One of Britain's top police officers used air miles collected during official trips to help buy flights for his family, it emerged today.
Metropolitan Police Assistant Commissioner John Yates broke his own force's policy by using the perk for private flights.
He agreed to pay back any outstanding tax owed on the trips, which are viewed by HM Revenue & Customs as a benefit in kind.
Mr Yates, 51, has led a number of high-profile investigations and is heading the reopened inquiry into allegations of phone hacking by News of the World journalists.
He has said he plans to interview the paper's former editor Andy Coulson, who is now David Cameron's director of communications.
The Mail on Sunday reported that the police chief used air miles from his work journeys to cut the cost of up to 10 flights taken by family members.
Under Scotland Yard rules, points amassed by officers as a result of official flights must be used to reduce the cost of future work trips.
Mr Yates, who was tipped as a future Metropolitan Police Commissioner, took nine official flights costing £32,000 to the United States, Canada, Australia, India and Kenya between February 2009 and February this year, according to expenses records seen by the newspaper.
As a senior Metropolitan Police officer, Mr Yates is entitled to travel business class when he goes abroad for work.
A Scotland Yard spokesman said: "All airline tickets are purchased by our travel section and use the cheapest and most appropriate flight for officers travel needs.
"AC John Yates had booked a small number of private flights using a combination of his own money and some of the air miles accumulated through business travel.
"He was unaware this is not in line with MPS policy and is clearly concerned. Should there be any tax implications arising from this then he will deal with these immediately.
"This is a timely reminder of a policy that may not be obvious and we will be taking steps to reinforce it to all of our staff."