THE Scottish Labour leader has attacked the Scottish Greens, branding them a “branch office” of the SNP amid news of an imminent co-operation deal between the parties.

The phrase “branch office” has often been used by critics to describe Scottish Labour in relation to the Westminster party. It is now the second time in a month that he used the descriptor to attack other parties.

It came as the SNP and Greens close in on a deal, and details could be released as soon as this week.

Nicola Sturgeon’s party has been in negotiations with the Greens since May, when the two pro-independence parties secured 72 seats together in the Holyrood election.

While a formal coalition deal is not on the agenda, an agreement is likely to see the parties work together on key issues – and could see Green representatives appointed to the Cabinet.

A source familiar with the negotiations said there had been “good progress” made and a deal was “95%” done.

Sarwar attacked Patrick Harvie and Lorna Slater’s party as a “branch office” of the SNP and added: “This coalition isn’t a surprise, it is just formalising a long-standing reality where Nicola Sturgeon and the SNP hammer our public services with cuts, and the Greens nod along.

“Scotland needs a real alternative that is standing up for our national recovery, the NHS and decent jobs – not the same old constitutional arguments.

“Scottish Labour are building that alternative, and I’d invite everyone in Scotland to join us on that journey.”

David Clark, a former Foreign Office adviser to Robin Cook, criticised Sarwar's comments.

"This rather Neanderthal attitude to coalition politics is a bit of a throwback to the worst of Old Labour," he said. "Are the SPD a branch office of the CDU in Germany? Labour needs to be better than this."

READ MORE: Anas Sarwar under fire for claiming Glasgow City Council is 'branch office' of SNP

Greens co-leader Harvie said Scots are looking for “grown up politics”, adding: “Green parties across Europe and in countries like New Zealand have in recent years rolled up their sleeves and worked with other parties to deliver a better future.

“But they have also shown that there is more than one way for government and opposition parties to work together, without losing the ability to challenge one another.

“We believe the people of Scotland want to see grown-up politics like this, and will approach the forthcoming talks in this spirit.”