"I do not feel able to continue in what I have experienced as a toxic and bullying SNP Westminster group," she said in a statement to the Daily Mail, referring to SNP lawmakers who sit in the British parliament.

The Scottish National Party has been battling divisions and a decline in its popularity since the sudden resignation of its charismatic Nicola Sturgeon leader in February and a financial scandal that damaged its image.

Cameron had previously spoken of being ostracised by colleagues after criticisng how the party handled sexual harassment allegations.

"I have no faith remaining in a party whose leadership supported the perpetrator's interests over that of the victims and who have shown little to no interest in acknowledging or addressing the impact," she said.

Conservative Prime Minister Rishi Sunak said he was delighted by her decision, in a post on messaging platform X.

The SNP did not respond directly to Cameron's criticism, but said she should now stand down as a lawmaker and trigger an election for her seat as Member of Parliament (MP) for East Kilbride, Strathaven and Lesmahagow in Scotland.

"Her constituents elected an SNP MP not a Tory (Conservative), and they deserve to have the democratic opportunity to elect a hard working SNP MP who will put the interests of Scotland first," an SNP spokesperson said in a statement.

(Reporting by William James. Editing by Andrew MacAskill)