An MP has apologised for calling one of his constituents a “little s**t” online.

Greg Mulholland (Lib Dem, Leeds North West) made the remark in response to a Twitter message from Leeds University student Jonathan Pryor about the gay marriage bill.

Mr Pryor had tweeted: "After abstaining, voting for a wrecking amendment, then trying to abolish marriage, I'm glad Greg Mulholland finally voted the right way.”

The MP, incensed at a remark that he claimed was part of “a dishonest and unpleasant campaign presenting me as anti- gay”, responded by tweeting: “I am very glad I have never met you Jonathan as you are a disingenuous, manipulative, illiberal little s**t!!"

Mr Pryor, a mature economics student, said he had been surprised by the MP's outburst: "I'm pleased lobbying by others and myself finally persuaded Greg Mulholland to vote in favour of equal marriage, but it appears scrutinising Greg's voting record is - as far as he is concerned - off limits."

Mr Mulholland said the principle of equal recognition was one he fully supported, but said the Marriage Bill was not equal on four counts, including that it continues to deny same sex civil partners the same pension rights as others and allows civil partnerships only for same sex couples.

"Whilst I am right to confront his intolerant and dishonest statements, I was of course wrong to call him a s**t."