Rishi Sunak has praised the bravery of an SNP MP who defected to the Conservatives just hours before she faced likely deselection by her local party.

The Prime Minister said Dr Lisa Cameron's decision to cross the floor was a sign that the Tories were "the party for those who will make constructive, long term decisions for a brighter future for the whole of the UK.”

The former SNP politician said she was deserting the party she had represented in the Commons since 2015 because of “toxic and bullying” treatment from colleagues.

She told the Daily Mail that after talking publicly about her mental health struggles she had received support from Mr Sunak in recent weeks but not from SNP leadership.

"Being in the SNP has been bad for my health," Dr Cameron said.

However, SNP sources pushed back at the claim, saying she had not been a team player for many years. 

They also suggested the Tories had tempted the MP over by offering the former consultant clinical psychologist a seat in the House of Lords.

Officially, the party said she should stand down and "allow a by-election". 

The defection comes just days before the start of the SNP's crunch conference in Aberdeen.

READ MORE: SNP MP threatens legal action against party in selection row

Dr Cameron was facing a challenge in her East Kilbride, Strathaven and Lesmahagow seat, and was at risk of losing the nomination to Grant Costello,  a local activist who works as the SNP’s Digital Media Manager.

The selection battle has been difficult for the MP, with little support for her to stay on in the role. 

Scottish Government minister, Christina McKelvie, the local MSP Collette Stevenson and former party grandee Linda Fabiani all called on members to oust the incumbent in favour of Mr Costello. 

Dr Cameron has blamed her potential deselection in part on her support for the teenage victim of Patrick Grady.

The Glasgow North MP was suspended from the Commons after he made an “unwanted sexual advance” to a teenage party staffer 19 years his junior “while under the influence of alcohol.”

Dr Cameron, a former consultant clinical psychologist, said she was "ostracised” by colleagues for asking about the victim. 

Explaining her decision to defect, Dr Cameron told the Daily Mail: ”I do not feel able to continue in what I have experienced as a toxic and bullying SNP Westminster group, which resulted in my requiring counselling for a period of 12 months in Parliament and caused significant deterioration in my health and wellbeing as assessed by my GP including the need for antidepressants.

“I will never regret my actions in standing up for a victim of abuse at the hands of an SNP MP last year, but 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.

“It is also true that I have received no contact from party leadership in the past weeks, despite members of every other main political party contacting me to offer support and compassion during what has been an extremely difficult time.

“I am particularly grateful to the Prime Minister in valuing my continued contribution to Parliament as a health professional and in taking time to listen. It is the first time I have felt heard and shows positive, inclusive leadership in contrast to that which I have encountered in the SNP at Westminster over many years.”

READ MORE: Cameron claims she's been shunned because of support for Grady victim

She also criticised the SNP’s commitment to independence, saying it had resulted in “significant division” for families like hers.

“This has taken its toll and I have come to the conclusion that it is more helpful to focus my energies upon constructive policies that benefit everyone across the four nations of the UK, and to move towards healing these divisions for the collective good."

She added: “Being in the SNP has been bad for my health. I will be taking time as advised to recuperate and will continue as always to focus upon serving my constituents.

“Thank you to everyone who has reached out to me who wishes to see a politics where victim blaming, and abuse is never tolerated.”

Mr Sunak said: "I am delighted that Lisa Cameron has decided to join the Conservatives. She is a brave and committed constituency MP.

"Lisa is right that we should aim to do politics better, with more empathy and less division and a dedication to always doing what we think is right.

"I look forward to working with her on the disability issues she has championed so passionately in parliament, and on the issues that really matter to her constituents in East Kilbride, Strathaven and Lesmahagow.

“Her decision is a sign that we are the party for those who will make constructive, long term decisions for a brighter future for the whole of the UK.”

Scottish Tory leader Douglas Ross said it was "great to have Lisa Cameron on board."

Writing on X, the site formerly known as Twitter, he added: "The @ScotTories will stand up for everyone who has been forgotten by the SNP to get the focus onto Scotland’s real priorities.

Labour's Ian Murray said: “This bizarre move shows that the SNP is falling apart before our eyes.

“The fact is that the SNP and the Tories are two sides of the same coin - putting the cause of division before the needs of the people.

“While the SNP and Tories compete to out-do each other in incompetence, Labour is focused on rebuilding our country and getting Britain its future back.

“Only a Scottish Labour MP will give the people of East Kilbride, Strathaven and Lesmahagow the fresh start they deserve.”

An SNP spokesperson said: “The people of East Kilbride, Strathaven and Lesmahagow will be appalled they are now represented by a Conservative and Unionist MP.

“Lisa Cameron should now do the right thing and step down to allow a by-election.

“Her constituents elected an SNP MP, not a Tory, and they deserve to have the democratic opportunity to elect a hard working SNP MP who will put the interests of Scotland first.

"On a personal basis, we wish her well.”