The Conservative Party chairman Grant Shapps has been accused of attempting to silence a critical left-wing blog in the run-up to the election by sending out spurious legal threats from lawyers.

Solicitors acting for Mr Shapps have written to the editor of the Political Scrapbook blog three times in the last six months, threatening to sue the publication over two articles about the party chairman.

The blog has also received a warning letter from the same firm of lawyers acting on behalf of another Conservative MP, who featured in the blog.

However, despite the warnings, no proceedings have been initiated against Political Scrapbook. The blog’s editor, Laurence Durnan, has accused Mr Shapps of “trying to shut down embarrassing stories”.

In one letter, lawyers for Mr Shapps accused the blog of writing a “false and defamatory” article about the Tory chairman’s local Conservative club. The blog had revealed that Mr Shapps’ election campaigns had been funded by a “secretive club” in his constituency which had been fined Financial Conduct Authority after refusing to reveal financial data or the names of its officers.

Despite only objecting to word “secretive” in the article, the letter from a city law firm demanded “the publication of a retraction, together with the removal of the misrepresentation from the article”.

It added: “In the event that this matter cannot be resolved without recourse to litigation we reserve the right to provide a copy of this correspondence to the court at the appropriate time in any such proceedings. We trust that this matter can be resolved expediently and without the increase in costs which would be substantial if this matter were to proceed.”

After receiving a subsequent letter about the matter, he pointed out the FSA fine and state the dictionary definition of “secretive” and no action was taken.

“This is pure and simple intimidation, designed to censor the publication of factually accurate stories which are strongly in the public interest,” he said.