Unions blast 'political' inquiry extension

The peak union body has attacked the federal government's decision to extend a royal commission into trade union corruption as "transparently political".

Australian Council of Trade Unions assistant secretary Tim Lyons said the move was unprecedented, with federal Attorney-General George Brandis extending the commission by a year without a request for more time being made.

"It's entirely unprecedented as far as we know for a government to extend a royal commission even though the commissioner didn't explicitly ask for it," Mr Lyons said.

Senator Brandis said on Tuesday a letter from Commissioner Dyson Heydon had made it clear that there was a large amount of unfinished business to be examined before the inquiry's December 31, 2014, deadline.

He announced the commission would have until December 31, 2015 to report and $8 million in additional funding on top of $53 million already allocated to investigate evidence of criminal conduct.

However, Mr Lyons pointed to the final paragraph of Commissioner Heydon's letter, which reads: "This letter is neither an application to widen the terms of reference nor an application to extend the reporting date".

The letter also states that the commission would meet its deadline and fulfil its terms of reference.

"This reveals once again the political motivations of the government," Mr Lyons said.

Mr Lyons said the government had decided to extend the unions commission within five days of receiving Commissioner Heydon's letter, while it had taken two months to respond to a request for more time and money from the child abuse royal commission.

The peak builders' body welcomed the extension, saying the royal commission had revealed evidence of instances of physical and verbal violence, secondary boycotts and cartel behaviour in the construction industry.

"The 12-month extension will allow the commission to more thoroughly examine these matters and recommend reforms necessary to enforce the rule of law in the construction industry," Master Builders Australia CEO Wilhelm Harnisch said.

The extension means the Heydon royal commission will run for more than 20 months - longer than the Cole royal commission which ran for 18 months from August, 2001.