Scottish Labour leadership hopeful Anas Sarwar claims he is the candidate Nicola Sturgeon fears, after the Scottish First Minister launched an outspoken attack on him at Holyrood.

The SNP leader hit out at Mr Sarwar at First Minister's Questions following reports a family firm he has a stake in fails to pay all workers the living wage.

After he told a leadership hustings that the living wage should be compulsory, Ms Sturgeon declared there is a ''gulf as wide as the Clyde'' between Mr Sarwar's words and his actions.

READ MORE: Nicola Sturgeon attacks Labour's Anas Sarwar over family firm living wage claim

The Glasgow MSP, who has previously served as Scottish Labour deputy leader, said: "Nicola Sturgeon's attacks clearly demonstrate who the SNP wants to win this contest.

"But I promise that if I am elected Scottish Labour leader I will work every day to remove her from office so that we have a government that puts Labour values at the heart of Scotland's future."

He added: "I can't wait to go head-to-head with Nicola Sturgeon at First Minister's Questions. If she wants to start early, that is fine with me."

Mr Sarwar is up against left wing MSP Richard Leonard in the contest to succeed Kezia Dugdale and become the fourth Scottish Labour leader in just three years.

Mr Leonard, a former GMB union organiser, has picked up all the trade union endorsements so far, with the shop workers' union Usdaw becoming the latest to back him.

He said: "I'm delighted to win the support of Usdaw, a union I have worked closely with to promote workers' rights in Scotland's retail, distribution and manufacturing industries for 25 years."

READ MORE: Nicola Sturgeon attacks Labour's Anas Sarwar over family firm living wage claim

A campaign spokesman added: "This is a fantastic endorsement for Richard's ideas. Usdaw have always been seen as being on the right wing of the Labour Party.

"Their support shows that Richard's message of real change is gaining support across the whole spectrum of Labour Party opinion, and that he is the candidate who can unite the party effectively."

Labour activists across Scotland will vote between the two men to decide who will be their next leader, with the result due to be announced on November 18.