British Prime Minister Gordon Brown wants a legally binding code of conduct for MPs as part of a plan to "clean up" Parliament.
Mr Brown told the BBC he also wanted a clean-up of all public institutions - such as the NHS and the BBC - in the wake of continuing disclosures over expense claims by MPs.
He told the Andrew Marr show that the abuses uncovered by the Daily Telegraph had offended his "Presbyterian conscience".
Conservative Party leader David Cameron is calling for an immediate general election to give the public an opportunity to get rid of MPs who have been caught up in the scandal.
But Mr Brown ruled out an early poll, saying: "I think what people want is to clean up the system first. To be honest, what I've seen offends my Presbyterian conscience. What I've seen is something that is appalling."
The BBC reports a new code of conduct would be written into the Constitutional Renewal Bill, due to be brought before Parliament later this year.
It is thought likely to include minimum service commitments to constituents, with those who break it facing possible fine or even ejection from their seats.
Mr Brown did not rule out "recall" elections for MPs who misbehave and said he was also setting up a committee to look at wider constitutional reforms, such as a bill of rights, a written constitution and House of Lords reform.
He did not rule out electoral reform, but said it was important to retain the link between MPs and their constituencies.