Tory leadership candidate Michael Gove has said he “deeply regrets” taking cocaine more than 20 years ago.
He told the Daily Mail that he had taken the drug at several “social events” while working as a journalist.
The environment secretary said he believed the “mistake” should not be held against him in his bid to become prime minister.
Members of the party are due to vote for a new party leader after Theresa May stepped down from the role.
Mr Gove, who served as justice secretary from 2015-16, is one of 11 Tory MPs who have said they intend to stand in the contest to replace her, with the winner expected to be announced in late July.
International Development Secretary Rory Stewart, who is one of those standing against him, has already apologised for smoking opium – a class A drug in the UK – at a wedding in Iran 15 years ago.
Boris Johnson – who is the favourite to succeed Mrs May as Conservative leader – was asked about claims he had taken cocaine at university by Marie Claire magazine in 2008.
He replied: “That was when I was 19.”
In an appearance on Have I Got News For You in 2005, he admitted being given the drug but suggested he had not actually taken it, saying: “I think I was once given cocaine but I sneezed and so it did not go up my nose. In fact, I may have been doing icing sugar.”
And Foreign Secretary Jeremy Hunt – another candidate – told the Times he had drunk a cannabis lassi while backpacking through India.
Mr Gove told the Mail: “I took drugs on several occasions at social events more than 20 years ago. At the time I was a young journalist. It was a mistake. I look back and I think I wish I hadn’t done that.
“I think all politicians have lives before politics. Certainly when I was working as a journalist I didn’t imagine I would go into politics or public service.
“I didn’t act with an eye to that. The question now is that people should look at my record as a politician and ask themselves, ‘Is this person we see ready to lead now?’
“I have seen the damage drugs can do to others and that is why I deeply regret the decisions I took,” he added.