The Serious Fraud Office has commenced an investigation over donations made to the Labour Party in 2017.
The SFO said in a statement this afternoon that it is presently conducting four investigations in relation to electoral funding matters.
A fifth matter that the agency investigated relating to electoral funding is now before the courts.
"We consider that making the current announcement is consistent with our past practice in this area of electoral investigations and in the public interest," the SFO"s director Julie Read said.
In the interests of transparency and consistency, the SFO announced the commencement of all these investigations, she said.
However, the SFO said it had no further comment to make on the Labour Party investigation.
The department's ongoing investigations include one into the New Zealand First Foundation and two other separate investigations into Auckland Council and Christchurch City Council mayoral electoral funding.
The fifth relates to donations paid to the National Party, which has led to criminal charges Independent MP Jami-Lee Ross and three other businessmen.
The Serious Fraud Office says it is on track to make a call before this year's election on whether to lay charges in relation to the New Zealand First Foundation, which has been bankrolling the New Zealand First Party.
Last week, Ross, New Zealand Order of Merit recipient Yikun Zhang, and brothers Shijia (Colin) Zheng and Hengjia (Joe) Zheng appeared in the High Court at Auckland after their case was transferred from the District Court to the higher jurisdiction.
The former National Party MP and three businessmen have all denied the charges against them over allegations about two $100,000 donations to the National Party.
The investigation was prompted by Ross going public with allegations against National leader Simon Bridges - which Bridges has adamantly denied - before he laid a complaint with police, sparking the SFO inquiry and his charges.
"I was the whistleblower. I still consider that I was right to raise the concerns," he has said. "There is no own goal."
A trial has been set for the National Party case in September next year.
Meanwhile, the SFO, which normally gives little away, has previously said its investigation into the New Zealand First Foundation faced challenges because of Covid-19.
"The SFO's pre-lockdown timetable for the investigation in relation to the New Zealand First Foundation would see us completing the investigation before the September election date," Read earlier said.
The SFO offices had been closed during the pandemic and the entirety of its workforce had been working from home rather than conducting face-to-face meetings.
In February the Electoral Commission said it believed the New Zealand First Foundation had received donations which should have been treated as party donations and had referred the matter to police to investigate.
The police referred it on to the SFO on February 11 and a week later the SFO launched a formal investigation.