The Northern Territory's Independent Commissioner Against Corruption has confirmed his office is investigating the NT government in relation to safety compliance issues at Darwin's major sports stadium.

In a statement, ICAC commissioner Michael Riches said he had yesterday launched the investigation into "certain matters" at Marrara Stadium.

The stadium is the home of major AFL and NRL games, and part of the Marrara Sports Complex, which is owned by the NT government.

While it was constructed in the '90s, it was never issued an occupancy certificate.

Mr Riches said his investigation would centre on the stadium's lack of occupancy certification, which is an offence under the Northern Territory's Building Act.

The decision comes after NT Infrastructure Minister Eva Lawler made a declaration on Wednesday that the stadium would be temporarily exempt from the key safety certificate.

"Yesterday the Minister made a declaration in respect of the facility of the kind provided for in section 65(1A). That was the first such declaration made," he said.

"The investigation I have commenced follows matters that have been brought to my attention about the facility and its compliance with the Building Act 1993, together with correspondence and information that I have received over the last several weeks from members of government, and others."

In 2020, the NT government admitted Marrara Stadium had never been granted an occupancy certificate proving it was safe to occupy.

At the time, the government insisted the stadium was still safe for spectators, and awarded a $23,000 tender to local company BCA Engineers to finalise the certification works.

However, in a special gazette published on Wednesday, Ms Lawler declared the stadium exempt from certification. 

She also revealed a new, $37,000 tender had been awarded to a separate company to complete the final compliance checks required. 

In a statement, Ms Lawler said the temporary exemption was designed to give the building certifier time to assess the facility and provide the required certificate.

She said the stadium was safe and the government was still working to secure certification. 

"Territorians have been using and enjoying TIO Stadium [Marrara Stadium] for 30 years," she said.

"The absence of an occupancy permit is a longstanding issue. DIPL is working to rectify this.

"A short-term exemption through a gazette notice has been issued in the interim."

Ms Lawler said the government would cooperate with any ICAC inquiry.