Brighton Pavilion’s outgoing Labour MP David Lepper is one of 20 MPs who broke parliamentary rules in accepting free overseas trips from foreign governments.
The BBC has uncovered hundreds of breaches in declaring hospitality in questions or debates.
Mr Lepper visited Cyprus every October from 2004 and 2009, and in August 2007, as the guest of the Municipality of Morphou, the Municipality of Famagusta and the Association of Cypriot Municipalities.
When he was joined by his wife, she paid her own air fares.
But on January 13, 2009, he tabled a parliamentary question without declaring an interest.
He also signed 29 early day motions relating to Cyprus without declaring an interest.
However, on other occasions when tabling or asking a question about Cyprus, and when signing 25 other EDMs about the country, he did declare the interest.
In response, Mr Lepper told the BBC: “If there have been occasions when I should have mentioned a registered interest and by oversight omitted to do so, I apologise for that.”
BBC home editor Mark Easton, who led the investigation, said it would raise further questions about the Commons’ ability to regulate itself.
The overseas visit rules are intended to ensure MPs cannot be accused of accepting foreign hospitality in return for political favours.