Nicola Sturgeon is poised to win Holyrood’s consent to take her independence referendum demand to Downing Street after the Scottish Greens confirmed their support.
Co-leader Patrick Harvie said his party will back the bid for a section 30 order, which provides the means of holding a referendum.
That gives the SNP’s minority administration the pro-independence majority required to win the backing of the Scottish Parliament next week.
Mr Harvie said: “The Greens welcome the Scottish Parliament’s consent being sought for a Section 30 order on an independence referendum and we will support it.
“Scotland’s votes and our voice have been ignored by a Tory government at Westminster which we did not vote for and a feeble Labour opposition.
“The people of Scotland deserve a choice between Hard Brexit Britain and putting our own future in our own hands.”
He said he has been “horrified” by the Prime Minister’s vision for post-Brexit UK, adding his party’s campaign will be for a “progressive, internationalist, independent Scotland”.
Having secured Holyrood’s support, Ms Sturgeon would be in a position to issue a demand to Theresa May for another referendum to be held.
Westminster would have to agree to the section 30 order, which temporarily transfers the power to Holyrood to hold a referendum.