The embarrassing slug is the latest in a string of cost increases for the problem-plagued project and comes as the city's council is struggling to rein in costs.

The proposal has been a leech on council finances from the beginning.

First mooted in 1999 by tourism groups, the Bulli Tops visitors centre was the subject of repeated assurances by council officers that the cost would come in under budget.

In 2003 the total cost was about $1.5 million. But by September 2007 that had jumped to $9 million, with $6 million to come from ratepayers.

As of yesterday, the ratepayers' share was set to jump to $7 million.

The council is blaming the collapse of the Howard government's Regional Partnerships Program, which was scrapped when Labor came to power last year, for the increase.

The council was forced to come to the rescue of the Illawarra Aboriginal Corporation, which found itself $900,000 out of pocket after the funding was withdrawn.

The money was earmarked for the fit-out of an Aboriginal interpretive centre inside the visitors centre.

In return for the money, the council will charge the Illawarra Aboriginal Corporation commercial rates for occupying part of the centre in an attempt to recoup its money within 10 years.

Perched high on the Illawarra escarpment the building sits astride the busy F6 and has picturesque views of Wollongong.

The piece of infrastructure has been a centrepiece to Wollongong's tourism strategy and will eventually include a tourist information facility and 250-seat restaurant along with the Aboriginal interpretive centre.

Construction work is well underway on the building, with about 80 per cent of the internal structure already built.

The building will be opened in early 2009.

The issue will be discussed at Tuesday night's council meeting.