Scotland's deputy first minister and leader of the Scottish Liberal Democrats, Jim Wallace, has announced he is stepping down.

Wallace will leave his dual roles once a successor has been chosen and will quit the Scottish parliament as MSP for Orkney at the next elections in 2007.

His announcement was a surprise, given the Scottish Lib Dems' positive election performance.

They took 11 seats and saw their share of the vote surge, putting them ahead of the Scottish National party and into second place.

But Wallace said it was time for him to step aside and make way for a new leader.

"Thirteen years as leader is a long time, and in that time, we have achieved more than I ever could have hoped for in 1992," he told a press conference yesterday.

"It makes sense, with two years to go to the next Scottish election, to make way for a successor. I have had the satisfaction of seeing the party grow and consolidate its position at every level over these last 13 years, culminating in our historic result last Thursday."