The Commons expenses watchdog has rebuked a Tory MP for writing "abusive and offensive" messages to its staff.
Backbencher Karl McCartney was accused of adding notes to claims, telling one official they were "talking s****", and condemning another as a "pedantic SOAB".
The criticism came after Mr McCartney claimed he was the victim of "bullying tactics" by the Independent Parliamentary Standards Authority (Ipsa).
During Business Questions in the House, Mr McCartney accused Ipsa chief executive Andrew McDonald of using "false innuendo and subterfuge" to smear the name of politicians.
"What do you think that subsequent to me raising these issues of Ipsa's senior management's bullying tactics and threats to try and silence me regarding their spiralling costs?" the Lincoln MP asked Leader of the House Andrew Lansley.
"Do you think that their chief executive should show some backbone and meet with me as he refused to do so for over two and a half years, instead of attempting to smear Members of Parliament's names by false innuendo and subterfuge?"
However, in a letter on Thursday evening, Mr McDonald denied the bullying allegations and insisted Ipsa was providing good value to the taxpayer.
He went on: "Some of the notes written by you, and attached to your claims, were recently brought to my attention.
"Having reviewed those notes, I was taken aback by the content, which ranged from the abusive ("you are a pedantic SOAB, aren't you?") through to the offensive ("you're talking s****") and on to the condescending ("simples - or didn't you do geography at Eton and Oxford...")."
He added: "I do not ask you to like Ipsa or its policies. At the same time, Ipsa's team deserves to be treated in a courteous manner. I ask that, with immediate effect, you desist from correspondence which falls below this standard."