The leader of the Scottish Liberal Democrats has defended his decision to bet on colleagues to win seats at the upcoming general election.

Alex Cole-Hamilton likened it to gambling on the Grand National, describing it as “just a bit of fun”.

But he contrasted it to claims that individuals close to government who may have had inside information had placed bets, which he said was a serious matter.

The Metropolitan Police is leading inquiries into a “small number of cases” potentially involving criminal offences, such as misconduct in public office.

BBC Newsnight has reported as many as 15 Conservative Party candidates and officials are being looked at by the Gambling Commission for alleged bets on the date of the election.

Scottish Secretary Alister Jack, who is not standing for re-election, has also said he placed three small bets in March and April on the election date but insisted he did not break any rules.

Labour has also dropped one of its candidates after it emerged he was under investigation for betting against himself.

Mr Cole-Hamilton said on Wednesday that he had placed some “low-level bets” to “show confidence in my friends”.

Speaking to BBC Radio’s Good Morning Scotland on Thursday, he said that was “entirely different” to placing bets using insider information.

He backed a review into gambling rules for politicians and officials but did not call for them to be banned on betting on the outcome of elections.

Mr Cole-Hamilton confirmed he had only bet on Lib Dem candidates, saying he would never be “so disloyal” as to back another party.

He denied knowing internal polling or party spend in those constituencies.

“Even if I did, you can’t predict the outcome of an election,” the party leader said.

“These things can swing wildly from week to week.”

He added: “I’ve lost far more than I’ve won, as I have with the Grand National, as I’m sure many of your listeners have done on the Grand National. It’s just a bit of fun.”

Mr Cole-Hamilton said what he had done was “entirely different” to having certainty about an issue and “taking that to the bookies with the hope of cleaning up”.

He said he was not aware of any Lib Dem candidates betting against themselves and said he would be “very concerned” if that was the case.

The UK Liberal Democrat leader, Sir Ed Davey, has already backed a review of betting laws.

He also said he had previously bet on the outcome of elections but drew a distinction between what he described as “having a flutter” and having inside knowledge before placing bets.

The Gambling Commission has not said who it is looking into but so far the names of five Conservatives have emerged, including three candidates.

Scottish Conservative chairman Craig Hoy said the gambling regulations governing politicians and those who work in politics should be reviewed.

Asked about Mr Jack’s election date bets, Mr Hoy said he would not have placed any himself but that it was for the Scottish Secretary to account for himself.

The Gambling Commission is also investigating Kevin Craig, who was a Labour candidate in Suffolk, for betting on himself to lose. Scottish Labour leader Anas Sarwar said Mr Craig’s behaviour was “completely unacceptable”.

In the BBC’s head-to-head TV debate, Labour leader Sir Keir Starmer accused Prime Minister Rishi Sunak of having to be “bullied” into taking action. Mr Sunak said he had handled the affair properly.

The SNP’s Westminster leader Stephen Flynn has said he is unaware of any party members being investigated by the Gambling Commission.