Paul Flowers, the former Methodist minister and chairman of the troubled Co-Operative Bank, today pleaded guilty to possessing drugs including cocaine and methamphetamine.

Flowers was suspended by both the Methodist Church and the Labour Party last year after he was caught in a drugs-related tabloid sting. He resigned from his position at the Co-Op amid claims about his use of expenses at the bank.

On admitting possession of Class A drugs, the 63-year-old was fined £400 in the Leeds court and ordered to pay £125 costs. He called a group of waiting photographers "vultures", according to news reports.

"Now that Paul Flowers has admitted guilt and been sentenced, our disciplinary process can move ahead," said a spokesperson for the Methodist Church.

"It is a confidential process so that all involved can speak freely, and it is independent of the Church leadership. We cannot give a deadline by which this work will be completed, but we would expect it to be before the summer."

Today a report into the sprawling Co-Operative Group, which had previously owned the ailing bank, concluded that the board of the Group is "manifestly dysfunctional" and called for reform.

The report's author, Lord Myners, said that the board needed to change to successfully oversee the businesses in the group, which range from funeral services to convenience stores.

"It places individuals who do not possess the requisite skills and experience into positions where their lack of understanding prevents them from exercising the necessary oversight of the executive," Myners said.

Flowers was appointed chairman of the bank in 2010 and had not had much banking experience at the time.

The Co-Op Bank had been hit by a £1.9bn funding gap, as well as the revelations about Flowers. The Co-Operative Group overall made a loss of £2.5bn last year. The bank is now majority owned by financial investors as part of a financial rescue plan.