Nicola Sturgeon's "bold" pledge to build 50,000 affordable homes falls short of what is needed to tackle Scotland's housing crisis, according to opposition politicians.

The Scottish First Minister promised that if the SNP is re-elected to government at Holyrood next year, it would spend £3 billion providing the homes over the course of the next parliament.

She hailed the commitment as a "mark of the ambition we have for this country".

But Scottish Labour housing spokesman Michael McMahon dismissed the pledge as "not ambitious enough to tackle the housing crisis Scotland is facing", while Jim Hume of the Scottish Liberal Democrats said it should be taken not with a pinch of salt but with "a fist of salt".

Ms Sturgeon had told the SNP conference housing would be "one of the biggest issues" in next year's Scottish election campaign.

She said: "Making sure that everyone has a safe, warm and affordable home is central to our Government's drive to make this country fairer and more prosperous.

"We have a good record on housing. In this parliament, we had a target of building 30,000 affordable homes and we are on track to meet it.

"We also started a new generation of council house building. And we have taken steps to safeguard social housing for the future by abolishing the right to buy."

But she added more "ambitious" action is needed, saying: "I am therefore announcing today a bold new commitment.

"If we are re-elected next May, our target in the next parliament will be to build at least 50,000 new affordable homes."

Housing campaigners at Shelter Scotland welcomed the pledge, with director Graeme Brown saying: "Shelter Scotland has been campaigning for a step change in the supply of affordable housing in Scotland for many years.

"We are glad that our calls have been heard and welcome the First Minister's pledge to deliver 50,000 new affordable homes over the next five years to help tackle Scotland's housing crisis. This is undoubtedly good news for people across Scotland.

"It is only by delivering a real step change in the supply of affordable housing that we can bring hope to the 150,000 households currently on waiting lists for a home in Scotland and the almost 5,000 children who will wake up homeless across the country tomorrow."

Approximately 35,000 of the new properties will be affordable homes for rent from either councils or housing associations.

Mary Taylor, chief executive of the Scottish Federation of Housing Associations, said: "We are extremely pleased that the SNP has listened to SFHA and others by committing to build 50,000 new affordable homes in Scotland, nearly double the target in the current parliament.

"The announcement of a pot of £3 billion in funding gives room for significant subsidy to the social housing element at affordable rents. This will help our members to plan programmes of affordable housing on the ground. Our sector stands ready to work with the Government to deliver this ambition."

But Mr McMahon said: "The fact remains this commitment is not ambitious enough to tackle the housing crisis Scotland is facing - a crisis the SNP have for too long ignored.

"A commitment to building 10,000 new homes per year is of course welcome news, and a welcome improvement on the 6,000 new social homes the SNP are building this year, but it falls far short of the number needed to tackle this crisis."

Mr Hume said: "The SNP have already reneged on their existing housing target. They promised to build 30,000 homes for social rent during this parliament but moved the goal posts to include affordable homes, pushing social housing to the margins.

"Shelter has said we need 10,000 new homes for social rent to be built each year to start to meaningfully tackle Scotland's housing crisis.

"This announcement may have gone down well in the conference hall but people living in communities screaming out for proper investment in socially-rented housing will take SNP promises on housing with a fist of salt."