By Justin Parkinson
BBC News political reporter
A Liberal Democrat MP has defended himself after swearing during a Westminster Hall debate.
Mr Mulholland said it had been "disgraceful" not to let him speak
Greg Mulholland called health minister Ivan Lewis an "arsehole" for not letting him intervene in a discussion on hospice funding, then stormed out.
Mr Lewis later said such language sent a "terrible message to young people".
But Mr Mulholland, MP for Leeds North West, accused the minister of being "cowardly" for not letting him speak.
During the debate, Mr Lewis criticised Mr Mulholland and his Lib Dem colleague Mark Hunter for turning hospice funding into a "party political issue", adding that this was "absolutely opportunistic and disgraceful".
Mr Mulholland, who spoke for about 10 minutes during the course of the debate, asked Mr Lewis to give way three times as the minister was giving his response.
After the third refusal, Mr Mulholland is quoted in Hansard - the record of parliamentary debates - as saying: "He's an a*******."
Mr Lewis then commented: "That was not very parliamentary language."
A spokeswoman for the Speaker of the House of Commons said she could not comment on whether a complaint had been received or an investigation was under way.
Mr Mulholland later told the BBC: "The minister's extraordinary rant was completely out of place in this debate, in which MPs from all sides contributed sensibly and sensitively to this important subject.
"It is sad that instead of listening to the very real concerns of the hospice movement and the problems of funding they face, he instead launched a nasty and misleading party political attack, then wouldn't let me respond to correct the record which was downright cowardly.
"He should be less interested in trying to score points and actually listen to issues of real concern in his area of responsibility.
"It is unfortunate that the official recorder picked up me expressing my anger about this performance to colleagues as I left the chamber, but I am certainly not the only one who thought that the minister's behaviour was disgraceful and uncalled for."
Mr Lewis responded: "It is sad that a debate on such a sensitive and important issue such as hospice funding was spoilt by Mr Mulholland's extraordinary behaviour.
"The two Liberal Democrat MPs were the only speakers who sought to make cheap and misleading party political points.
"The fact that I rebutted their attacks prompted an outburst unbecoming of a parliamentarian."
Mr Lewis added: "I hope Mr Mulholland will reflect on the fact that the use of such language is not only inappropriate but sends out a terrible message to young people about the importance of decency and civility.
"This is now a matter for the Liberal Democratic leadership."
Last month, Hansard had to be changed after Armed Forces Minister Bob Ainsworth was recorded to have muttered "absolute bollocks" during a Commons debate on troops' kit shortages.
Unparliamentary language - which includes that which is insulting, coarse, or abusive - is banned, as are accusations of lying, being drunk and misrepresenting the words of another MP.
Among the words to which Speakers have objected over the years are "blackguard", "coward", "git", "guttersnipe", "hooligan", "rat", "swine", "stoolpigeon" and "traitor".
The Speaker has the power to direct an MP who has used an unparliamentary word or phrase to withdraw it.
An MP who refuses to retract an offending expression may be "named", after which the Commons can vote on whether to suspend them.