Tory MP Charlotte Leslie is facing an official anti-sleaze probe over allegations she broke the rules on disclosing donations.

The move comes after rising star Ms Leslie – tipped as a future Tory Minister – failed to register donations of £28,000 made to her local Tory association.

She is now the third Tory MP facing investigation. Former Tory shadow minister Patrick Mercer, now an indepent MP, could be suspended from the Commons after being caught in a cash-for-questions scandal and Tory MP Peter Bone is also under investigation.

Labour MP Chris Evans has written to the Parliamentary Standards Commissioner Kathryn Hudson to demand an inquiry over claims Ms Leslie has breached the MPs’ code of conduct.

House of Commons: Where MPs work (pic credit: Alan Cleaver)

Ms Leslie has already apologised for a “serious error” after raising concerns about the Severn Barrage project – without telling Parliament she had accepted £28,000 from one of the main opponents of the scheme.

Bristol North West MP Ms Leslie has questioned the impact of the proposed barrier across the River Severn several times at Westminster.

But she failed to tell MPs she had accepted three donations totalling £28,000 between March 2009 and June 2013 from David Ord, the joint owner of Bristol Port which opposes the project.

Welsh Labour MP Mr Evans told the Sunday Mirror yesterday that Ms Leslie had questions to answer over the donation and should have copied other MPs by referring herself voluntarily to parliamentary watchdogs.

In his letter to the Standards Commissioner, Mr Evans said: “I do not believe it is enough for Ms Leslie to assert that she did not benefit personally, nor do I believe the circumstances in which questions were asked in Parliament have been adequately explained.

“Indeed I felt sure that she would refer herself to the Commissioner for Standards; however, this does not appear to have happened. I am therefore writing to formally request you investigate what appears to be a breach of the Code of Conduct.”

Oxford-educated Ms Leslie said she was “unspeakably sorry” for failing to declared the donations at Westminster, although she had told watchdogs at the Electoral Commission about the cash.

However, she irritated some constituents and politicians by blaming her mistake on dyslexia.

One Whitehall source said: “Charlotte Leslie is an intelligent woman, but she is insulting dyslexia sufferers by suggesting her condition meant she couldn’t follow basic rules on registering donations.

“She was quick enough to intervene with detailed questions about the Severn Barrage, but failed to declare the important fact the she had received cash from one of the project’s rivals.”