A Scottish National Party MP has described the DUP’s influence on the government over the Brexit deal as “incredibly unhealthy”.
Gavin Newlands said it was wrong one party had more sway than the Scottish and Welsh Parliaments combined.
The DUP has been talking to the government about what it would take for its 10 MPs to back the agreement.
The votes of the DUP MPs are crucial for the government in getting its Brexit deal through Parliament.
Conservative Brexiteer MPs, including Jacob Rees-Mogg, have said they will wait for the DUP’s verdict on any deal before deciding whether to back it in another vote.
On Monday, Scottish First Minister Nicola Sturgeon wrote to Prime Minister Theresa May about the role of the devolved administrations in talks on the future trade relationship between the UK and EU.
She said she wanted to seek clarity from Mrs May about press reports that the DUP could be offered a seat at the table in future trade talks.
Ms Sturgeon said she was concerned the PM’s strategy for securing a majority for her deal was to accord the DUP “disproportionate influence”.
“It seems clear that maintaining your majority in Parliament comes before respect for the properly constituted governments across the UK,” she wrote.
She added there could “be no question” of one political party – the DUP – being represented in future UK-EU trade talks when other political parties and devolved governments are not.
The DUP has said its negotiations with the government are not about anything other than ensuring the constitutional integrity of the UK is maintained.
But on Sunday, Chancellor Philip Hammond declined to rule out a financial settlement for Northern Ireland if the DUP backed the deal.
Gavin Newlands, the SNP spokesperson for NI affairs, said the DUP’s “incredibly unhealthy” influence over the government in the Brexit talks was entirely down to how the prime minister had handled the entire process.
“Had she reached out to opposition parties at the very start she may have been able to find consensus,” he said.
He said the SNP did not have an issue with Northern Ireland receiving more money from the government, but argued that all devolved regions should be given more expenditure from the Treasury.
“Scotland has been ignored at the expense of the DUP and electoral math in the UK Parliament,” he added.
“The DUP just by the event of an election have that influence.”