Kemi Badenoch, the leader of the Conservative party, has accused Nigel Farage of being an opportunist who does not believe in unionism after he urged Scottish nationalists to back Reform.

Farage said earlier this week he believed “genuine nationalists” would not support the Scottish National party’s bid to rejoin the EU, and urged them to vote Reform in the Holyrood election on 7 May.

He also told the Scotsman that while he believed in the UK, it was “probably quite reasonable” to hold a second independence referendum in the future, “if this issue came back”.

Badenoch, speaking to reporters in Edinburgh on Thursday, said only her party was truly centre-right and unionist. “Nigel Farage doesn’t really believe in anything except Nigel Farage. He tells everybody what they want to hear,” she said.

“If he’s speaking to a unionist, he’s a unionist. If he’s speaking to a nationalist, he’s a nationalist. This is how Reform managed to vote for and against the two-child benefit cap on the same day in the same vote.

“They don’t know what they stand for, except that they are against everything and everybody that is part of the system. They can see problems, but they don’t have the solutions.”

The Conservatives are fighting a desperate battle to prevent Reform taking tens of thousands of votes from them at the election.

The Conservative party is Holyrood’s second-largest party, but opinion polls consistently show it lagging behind Labour, Reform and the Scottish Greens, and level with the Lib Dems, on about 8-13% of the vote.

Malcolm Offord, Reform UK’s Scottish leader, fuelled Badenoch’s allegations that Reform intend only to disrupt British politics after he confirmed his party would not block the Scottish National party leader, John Swinney, from being voted in as first minister if it came down to a knife-edge vote in Holyrood.

The SNP is widely expected to comfortably win the election, with some polls suggesting they could win a majority. If the party does, Swinney confirmed on Thursday that he intended to demand a second independence referendum by 2028, despite the UK Labour government stating it would not authorise that.

It is known that Scottish Labour and the Lib Dems hope that after the election anti-SNP parties could command enough votes at Holyrood to get Anas Sarwar elected as first minister instead, backed by the Tories, even if the SNP were the largest party.

But if Reform UK succeeds in winning 10 or more seats, as the polls suggest, its votes could be crucial.

When Offord was asked on Wednesday whether the he would work with Labour to keep the SNP out, he said: “No. Because we are the challenger party.”

In a sign of a concerted anti-SNP sentiment, some senior Tories are urging anti-independence voters to vote tactically to block the SNP from winning seats at Holyrood, in defiance of Badenoch’s insistence that Tory voters needed to vote Conservative at all times.

David Mundell, who was Westminster’s Scottish secretary from 2015 to 2019, urged people to vote tactically in a social media post. He told the Commons on Wednesday that “anybody in Scotland who doesn’t want to see Scotland spend the next five years in a constitutional cul-de-sac should use their votes wisely to stop an SNP majority”.