Charles Kennedy yesterday refused to rule out the prospect of becoming leader of the Liberal Democrats again.

Appearing at the Scottish Parliament's festival of politics, he said he had no regrets about his decision to stand down last year after admitting he had a drink problem.

But he failed to deny persistent rumours that he would be prepared to replace Sir Menzies Campbell, whose leadership of the LibDems has been called into question repeatedly since he succeeded Mr Kennedy.

During an hour-long question-and-answer session in the Holyrood debating chamber, the MP for Ross, Skye and Lochaber also challenged Alex Salmond to hold a referendum on independence "next week", contradicting the stance of his party north of the border.

Addressing the continuing concerns about his battle with alcoholism, Mr Kennedy said: "My health is good, I'm happy and fulfilled with what I'm doing and it's up to me to keep it that way, which I am."

While he said he has enjoyed his return to the back benches since his resignation in January 2006, he failed to provide a straight answer to a woman in the audience who asked if he was "going to be the comeback kid" and regain his party's leadership.

The 47-year-old said: "When you've been the leader of a national political party, you know what's involved and you're still of an age that you could contribute but you don't have the same demands on you in quite the same way.

"That can be a happy set of circumstances. You can still use your influence, but without having constantly to look over your shoulder and beat off the considerable demands of your party and the all-consuming demands of the media .

"As a former leader, you have more time to think more closely about how we communicate and engage. Which is not an answer to your question."

Another member of the audience asked Mr Kennedy what question he would ask Alex Salmond at First Minister's Questions if he was an MSP.

He replied: "If I was being mischievous, I would probably ask him, as several people have, if you think independence is the way forward and you've published a bill on it, why not put it to the test next week'?"

His comments echo those of Lord Forsyth, the former Tory secretary of state for Scotland, and the Labour Scotland Office minister David Cairns, who have also called for a referendum to take place.

However, the Scottish LibDems refused to form a post-election coalition with the SNP over the issue, and remain steadfastly opposed to it.

A spokesman for Mr Salmond yesterday pounced on Mr Kennedy's comments.

He said: "Charles Kennedy's remarks indicate yet another division of opinion in the Liberal Democrat ranks."