MP is 'sorry' for offensive messages.
The Independent Parliamentary Standards Authority (Ipsa) disclosed that Karl McCartney had sent messages telling one official they were "talking sh***", and condemning another as a "pedantic SOAB".
The jibes emerged after Mr McCartney claimed he was the victim of "bullying tactics" by the watchdog.
During Business Questions in the House yesterday morning, 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.
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 sh***") and on to the condescending ("simples - or didn't you do geography at Eton and Oxford...").
"In the light of your comments today, I write to ask that you conduct your dealings with us - orally or in writing - in civil terms."