SCOTLAND must increase its number of MSPs at Holyrood as more powers are devolved from Westminster, a former first minister has claimed.

Henry McLeish told an audience at the Scottish Parliament that there is “a limit to what you can do” with the present number of 129 MSPs and that Holyrood should be "more ambitious".

Speaking at the 20 Years of the Scottish Parliament debate on devolution, the former Labour leader said that Holyrood would need “to think quite seriously about where the numbers in the parliament may be going in the years ahead” if committees were to scrutinise governments and other public bodies properly.

“To be fair to them, I think a lot of fantastic work has been done, but you cannot keep pouring a quart into a pint pot, so something has got to give,” he said. “So I feel that we should be more ambitious about how we look at this.”

McLeish helped steer the Scotland Act, which re-established the Scottish Parliament, through the House of Commons when he was devolution minister in the 1990s.

He also called for the first-past-the-post voting system to be scrapped and for politicians to be elected under an entirely proportional system.

Holyrood’s 129 MSPs are elected using the additional member system, which gives each elector two votes, one for a constituency MSP and one for a regional party list.

The smaller parties are more likely to secure a route into parliament via the list because the voting system is designed to make the result more proportional overall.

The SNP has 62 MSPs, the Tories have 31, Labour has 23, the LibDems have five, the Greens have six and there is one independent and one with no party affiliation.