The leader of the Victorian Labor Party has avoided comment on more media reports ahead of this week’s union corruption inquiries.

It comes after another report has appeared in Australian newspapers, seemingly containing evidence which will be formerly introduced to the Royal Commission when it kicks off in coming days.

A story in News Corp media outlet The Herald Sun says an unnamed Labor Party official demanded $50,000 to protect a prison re-development project from Construction, Forestry, Mining and Energy Union (CFMEU) industrial action.

Victorian Planning Minister Matthew Guy said this sort of thing does happen.

“Developers have told me a number of examples where they have felt high pressure, or extorted, by a range of organisations - predominantly unions - and I have advised them to just go and tell the relevant authorities,” Mr Guy said.

Labor leader Daniel Andrews says judgement of these claims should be left to the Royal Commission, not the court of public opinion.

“Those issues that have been canvassed in the media in the last 24 hours are undoubtedly very serious issues,” Mr Andrews told reporters on the weekend.

“The appropriate thing to do is for those matters to be looked at carefully by the royal commission, and I do not propose to provide a day-by-day, blow-by-blow, commentary on the work of the royal commission.

“When the royal commission's work is finished ... I will have no hesitation on acting on any finding that the royal commission should bring forward.”

The CFMEU has reportedly sent out a letter to its members and to the commission, in which it raises concerns about “selective and unfair briefings of journalists by commission staff”.