Wollongong City Council has brought in an independent surveyor to find out how more than $2 million in public money was spent to relocate two Wollongong football clubs to Lysaght Oval.

Behind closed doors, the council is trying to get to the bottom of how the $2.5 million grant was spent and is still refusing public access to key documents.

The matter has already been referred to the Independent Commission Against Corruption by the NSW Premier's Department, which initially released the grant.

An unnamed Sydney-based firm this week started poring over invoices related to the Premier's Department funded project intended to finance the relocation of Wollongong FC and Wollongong Olympic from Brandon Park to Lysaght Oval.

The funds, held in trust by the council, will be frozen until the investigation is finished early next month. The firm will compare invoices submitted by developers Wollongong Sport and Recreation Centre Pty Ltd, with work completed at the Figtree ground.

Just over $400,000 is left of the $2.5 million earmarked for the project in two instalments from 2002 and 2003.

The council, as the grant's trustee, is responsible for the release of funds for work at the complex.

"A number of questions have been raised both to council and publicly about the provision of work at the site," council general manager David Farmer said.

"As a result, council feels the most appropriate course of action is to engage an independent expert to compare work completed at Lysaght Oval with the claims made to date."

Earlier this month, a council spokesman said all money spent from the grant had been backed by supplier invoices and legal declarations that the work had been completed.

But the council has not released the invoices or offered details of who got the money.

The council's administrators have also failed to answer questions on the matter and information requests have been met with refusals.