The Serious Fraud Office (SFO) says it is looking into "multiple complex cases of potential fraud" involving the COVID-19 wage subsidy.
The Ministry of Social Development (MSD), which administers the subsidy, earlier this year said it had resolved thousands of complaints but was investigating hundreds more.
More than $14 billion was paid out under the scheme last year and a few more billion has been spent this year, the generous payments credited with keeping job losses to a minimum during periods of lockdown.
To qualify, businesses must either experience - or provide evidence they are likely to experience - significant revenue losses as a result of level 3 or 4 lockdowns, and make efforts to minimise this. Employers have to name the employees they'll be supporting with the subsidy, and use their "best endeavours" to pay them 80 percent of their usual salary, or the value of the wage subsidy at minimum.
"Last year, the SFO received funding from the Government to specifically tackle fraud arising from the COVID-19 pandemic," the SFO said in a statement on Friday.
"Investigating allegations of serious abuse of the COVID-19 wage subsidy meets the mandate for that funding.
"We are pleased to be supporting the extensive work already being undertaken by MSD in response to abuse of the COVID-19 wage subsidy, by contributing the expertise of our specialist investigative teams to look into cases of a particularly challenging and complex nature."
The SFO said it would not comment any further while its investigations were being carried out.