A former British chairman of the Co-operative Bank has apologised after a newspaper reported that he has been caught buying and using illegal drugs including crystal meth, crack cocaine and ketamine.

The Mail on Sunday said the Rev Paul Flowers, a Methodist minister, was filmed buying the substances.

The alleged dealing took place just days after he was grilled by the British parliamentary Treasury Select Committee over the bank's disastrous performance.

The newspaper said the 63-year-old reverend - who has been suspended by his church - is seen in his car in a video discussing buying cocaine and crystal meth from a dealer in Leeds.

He reportedly then counts out £300 (€358) in £20 notes and sends a friend to make the deal.

The video and a series of text messages were handed to the newspaper by an acquaintance of Rev Flowers who was "disgusted by his hypocrisy", it said.

The Rev Flowers, who chaired the Co-operative Banking Group and the Co-operative Bank for three years is a former Labour Party councillor who once chaired the drugs charity Lifeline. 

The text messages suggest Rev Flowers was using hard drugs in the days surrounding his testimony to the Treasury Committee on 6 November, the newspaper claims. 

On the day after his appearance at the Commons, he sent a text reading: "I was 'grilled' by the Treasury Select Committee yesterday and afterwards came to Manchester to get wasted with friends."

The newspaper said Rev Flowers also boasts of using illicit substances including ketamine, cannabis and club drug GHB.

"This year has been incredibly difficult, with a death in the family and the pressures of my role with the Co-operative Bank," Rev Flowers said in a statement.

"At the lowest point in this terrible period, I did things that were stupid and wrong. I am sorry for this and I am seeking professional help, and apologise to all I have hurt or failed by my actions."

The Co-op has been trying to plug a £1.5bn (€1.79bn) gap in finances which was discovered following the purchase of the Britannia Building Society and abortive plans to buy hundreds of Lloyds branches.

Rev Flowers has been a Methodist minister for 40 years, currently in Bradford. 

The Co-operative Bank declined to comment.

A Methodist Church spokesman said: "We expect high standards of our ministers and we have procedures in place for when ministers fail to meet those standards.

"Paul is suspended from duties for a period of three weeks, pending investigations, and will not be available to carry out any ministerial work. We will also work with the police if they feel a crime has been committed," the spokesman added,