Kate MacLean, who represents Dundee West, said she had used the drug from her "late teens to early 20s" but that it did not affect her position.

Morag Kinniburgh reports: "Scottish Parliament cannot change the law"

But fellow committee member, Conservative MSP Phil Gallie, said: "My concern is she doesn't seem to be acknowledging that it was wrong.

"She is on the justice and home affairs committee. We are there to assist in making the law, we are certainly there to ensure that the law is upheld and for someone to condone the breaking of the law seems to me to be inappropriate."

Her confession was made in a response response to a survey conducted by the Big Issue magazine.

Medical use

The magazine has said three other Labour MSPs who responded called for cannabis to be made available for patients who are chronically ill.

The mother-of-two, who took the Dundee West seat with a majority of just 121 in the May elections, was the only Labour MSP to admit to having used cannabis.

Kate MacLean: "I'm surprised at the level of interest"

The Scottish Executive has defended the MSP, despite a disclosure which could have an impact on the public view of its highly publicised fight against illegal drugs.

She told BBC Scotland: "I think something I did 20 years ago doesn't affect the work I do as an MSP now.

"I don't think it affects the way that I will perform on the justice committee or in any other part of my work as an MSP.

Kate MacLean: "Honest debate"

"I don't think I have enough information to say whether I would be in favour of decriminalising cannabis or not but I do think we need an honest debate about the use of cannabis.

"Twenty years ago the kind of social scene I was involved, in lots and lots of people smoked cannabis. When I got married and had kids, I didn't do it any longer."

She said she was grateful for the support of First Minister Donald Dewar and added: "I regret if this has caused any embarrassment."

A spokesman for First Minister Donald Dewar said: "She answered the survey honestly. This all happened a long, long time ago. It has no reflection on what she does now."

Commission call

The formal remit of the parliament's justice committee is: "To consider and report on matters relating to the administration of civil and criminal justice, the reform of the civil and criminal law and such other matters as fall within the responsibility of the Minister for Justice."

This includes "criminal policy in relation to drugs".

Margo MacDonald: I admire Kate MacLean"

Scottish National Party MSP for Lothians, Margo MacDonald, currently has a motion before the parliament asking for a specialist commission to investigate the use of cannabis in Scotland and recommend any changes to the legal system.

She said of Kate Maclean's admission: "I admire her very much indeed.