United Future leader Peter Dunne says secret tapes and claims of stolen papers are a new low in politics.
The National Party has accused Labour of making secret recordings of conversations with at least three of its MPs.
It also says someone went through the rubbish of its leader, John Key.
And police are investigating a break-in at the Auckland electorate office of Health Minister David Cunliffe.
Mr Dunne says the public does not see these issues as part of the electoral process.
He says Mr Key and Prime Minister Helen Clark need to issue clear statements saying they do not condone dirty tricks.