The federal opposition says newly revealed documents show the government and Fair Work Australia (FWA) have colluded.
The industrial watchdog's website shows email contact from August 2011 between Rhys Davies, a staffer of then workplace relations minister Chris Evans, and FWA's communications manager Judy Hughes.
In the exchange of emails, Mr Davies asked Ms Hughes if claims made by the Seven Network that Labor MP Craig Thomson lied to FWA were true.
In one of her replies Ms Hughes sent Mr Davies a statement issued to journalists confirming there was no new inquiry into Mr Thomson.
Mr Davies replied he was pleased with that news.
'Thanks that's awesome should minimise any run it gets in the morning,' Mr Davies wrote.
Coalition frontbencher Christopher Pyne said the contact is at odds with what government MPs have been saying.
'For months and months the prime minister has insisted that there is no collusion between Fair Work Australia and the government,' Mr Pyne told Sky News.
'And yet these emails that have been exposed tonight on Channel Seven news clearly indicate that the office of the Minister for Industrial Relations at the time was involved with Fair Work Australia in getting assurances from them of the way they were handling media stories at the time in August last year.'
Industrial Relations Minister Bill Shorten said the claims are old and have been in the public domain before.
'I understand some of those emails were reported in an answer in parliament on December the ninth,' he told ABC television.
'What the Liberal Party's doing here, as they will, is they're dressing up old news and presenting it as new news.'
Mr Shorten said he is not aware of any contact between the government and FWA other than what has been reported in parliament.
'If you look at the parliamentary hansards throughout the last two years, whenever there has been any contact it has been reported in the parliament,' he said.
