A former Victorian Labor Party operative arrested before dawn on Thursday claims he was strip-searched before being interviewed by detectives.

At least five former Labor field organisers were arrested for questioning as part of the fraud and extortion squad’s investigation into the ALP’s misuse of taxpayer-funded staff during the 2014 state election campaign.

Police say 17 people will be questioned in Victoria, New South Wales and the Northern Territory.

No charges have been laid and no Labor MPs were arrested.

Jake Finnigan, who blew the whistle on Labor’s scheme, said he was arrested by two detectives at 5.55am for “making a false document” and taken to the Melbourne West Police Station.

He said he was strip-searched before being put in a cell and police removed the drawstring from his shorts.

But when asked if his treatment seemed excessive, Mr Finnigan said police were just doing their jobs.

“I am co-operating with police throughout this matter,” Mr Finnigan said.

“I’m glad to see that this rorts investigation is finally reaching a point where things are going ahead.

“I’m just completely sick of what’s happened in this state and that it’s taken this long to get here.”

Mr Finnigan was in the cell for 15 minutes before his interview, and was returned home just before 8.30am.

Labor’s state secretary Samuel Rae said the party was co-operating with investigators, but took aim at the methods used by police.

“Conducting dawn raids on people’s homes was completely unnecessary given those involved would have co-operated if asked,” Mr Rae said.

“That had already been communicated to Victoria Police by our lawyers earlier this week.

“We have also received a number of concerning reports about the raids, including that some of those questioned were told by Victoria Police that they did not need legal representation during the interview process.”

Victoria Police has been contacted for comment.

Opposition Leader Matthew Guy is pushing for ministers to be stood down. Photo: AAP

Lawyer Rob Stary is advising Labor and questioned the use of the raids.

“There’s no national security issue. There’s no organised crime issue. These are ordinary individuals, working people often with families,” he said.

“To be raided in the fashion that they were … is highly unorthodox.”

Government cancels media events

Other Labor figures were privately angry about the early morning arrests and could not understand why those people were not simply asked to come in for a interview.

The Andrews government declined to comment, and a number of media events planned for Thursday in regional Victoria and involving ministers were cancelled.

Police announced last week they would open a formal investigation into Labor’s misuse of electorate staff.

In March, the Ombudsman found Labor had wrongly used $388,000 of taxpayer funds to have electorate officers work as campaign operatives in marginal seats during the 2014 election campaign.

Labor repaid the money but insists that it did not deliberately break the rules.

Twenty one former and current Labor MPs were implicated by the Ombudsman, including six ministers.

Opposition Leader Matthew Guy said the government was centred on saving its skin, to the detriment of the state.

“The government can’t sustain this any longer,” Mr Guy said.

“A government in crisis is a government focused on itself, not on Victorians, and the Andrews government is in total crisis,” he said.

“Those six ministers must stand down from their positions, for the sake of integrity, for the sake of respect for all Victorians, for the sake of respect for the institution of government.”

But Mr Finnigan said other political parties were also involved in misusing electorate entitlements.

He said Labor’s field organisers should not be singled out in the investigation.

Mr Finnigan plans to run as an independent candidate for Footscray at the November 24 state election, on what he said will be an “anti-corruption platform”.

“It’s now at the point where instead of taking shots from the sideline, I’m actually going to get involved,” he said.

Mr Finnigan has already backed the opposition’s calls for ministers to stand aside during the investigation, especially Attorney-General Martin Pakula and Police Minister Lisa Neville.

“There is no way we can have any confidence in this investigation while they are still at the helm,” he said.

Earlier this week, Deputy Premier James Merlino asked police to investigate 18 Coalition MPs for allegedly rorting taxpayer funds and misusing electorate staff, but refused to release any evidence to support the claims.

He also claimed a number of ministerial staff were used by the Napthine government for its re-election campaign in 2014, but they did not take leave from the jobs, meaning they were paid for by the taxpayer.

The opposition said the claims were farcical and accused Labor of trying to “muddy the waters”.

-ABC