Britain's prime minister says the Co-operative Bank will face an independent inquiry into the role of its former chairman, a minister who was filmed allegedly buying crystal meth and other drugs.

Paul Flowers, a Methodist minister who led the bank for three years until he stepped down in June, has apologized after footage of him allegedly buying drugs emerged this week. The Mail on Sunday reported that he bought the drugs just days after lawmakers grilled him on the bank's disastrous finances.

Prime Minister David Cameron told lawmakers Wednesday that "many questions have to be answered" regarding the Co-op Bank, including why Flowers was judged suitable to be its chairman in the first place.

The Methodist Church said Wednesday that Flowers had been suspended indefinitely from his post as minister.