Nicola Sturgeon’s minority government and the Scottish Greens are expected to confirm their delayed power-sharing agreement after months of intense negotiations, ushering the Greens into government for the first time anywhere in the UK.

The specifics of the deal, which stops short of a formal coalition, are expected to be announced later on Friday after the plans have been given final approval by the Scottish cabinet, and mark the first time the Scottish National party has shared power at Holyrood during 14 years in government.

It must then be confirmed by Scottish Green members on 28 August, a tight deadline given it happens only three days before Sturgeon addresses MSPs on her programme for government.

The Guardian has previously reported that the Scottish Greens anticipate the deal will include the appointment of two Green MSPs – expected to be their co-leaders, Patrick Harvie and Lorna Slater – as junior ministers.

In anticipation of the announcement, opposition parties criticised the deal. The Scottish Conservatives described the Greens as “extremists” who “don’t belong anywhere near government”, while Labour condemned it as a “coalition of cuts”, claiming it “confirms the long-held suspicion that the Scottish Greens are just a branch office of the SNP”.

After the SNP fell one seat short of a majority in May’s Holyrood elections, the pact will formalise the majority in favour of independence.

The unique arrangement, which will not amount to full coalition, where both sides are bound by collective responsibility, is understood to have proved challenging for civil servants who have had to draw up a new set of rules governing the obligations and capacity for dissent for both sides.