A leading law firm has been found "in contempt" of the Commons after threatening an MP with legal proceedings if he made allegations about one of its clients in the House.

The Standards and Privileges Committee criticised Withers LLP for failing to realise that John Hemming, a Liberal Democrat backbencher, was protected by Parliamentary privilege.

The firm of solicitors had urged the MP to withdraw what they called "defamatory" claims about property developer Jeremy Knight Adams.

They later sought an assurance that he would not repeat the allegations in the Commons, saying that without it they would issue proceedings.

Mr Hemming refused to give the undertaking and advised that the firm's actions might be regarded as contempt of Parliament. Withers dismissed his warning as "inappropriate".

Only after consulting counsel, following a further warning from Clerk of the House Malcolm Jack, did Withers accept it had been "mistaken" and apologised to the Commons and Mr Hemming.