The royal commission into the Labor government’s failed insulation scheme will hear from former minister Peter Garrett.

Former Labor government minister Peter Garrett has been granted leave to appear at the royal commission into the botched insulation scheme.

Mr Garrett, a former environment minister who retired from politics in 2013, played a key role in rolling out the economic stimulus scheme.

The inquiry, under commissioner Ian Hanger QC, is seeking new light on the deaths of four workers involved in the insulation scheme and what warnings were given to the Rudd government.

The commission confirmed on its website that Mr Garrett had been granted leave to appear and have legal representation, along with the federal and Queensland governments and family members of the dead men.

In February, former prime ministers Julia Gillard and Kevin Rudd were ordered to hand over documents relating to the scheme.

But they are not listed as witnesses.

It is understood other former ministers Lindsay Tanner, Penny Wong, Greg Combet, Mark Arbib and Wayne Swan have been contacted by the commission and shadow attorney-general Mark Dreyfus is providing advice.

Prime Minister Tony Abbott has also approved the release of former Labor cabinet documents to the royal commission but reserved the right to exercise public interest immunity over the papers.

A second public hearing is expected to be held this month, following the inaugural hearing on December 23 last year.

Matthew Fuller, Rueben Barnes, Mitchell Sweeney and Marcus Wilson all died while working on the $2.8 billion “pink batts” program established by the Rudd government in early 2009.

The men’s families have blamed the rushed rollout of the program and lax standards for the deaths.

The inquiry report is expected by the end of June.