WORK on the delayed £29million sports complex at Ravenscraig will start next month despite concerns over the cost of shoring up the site.

The long awaited project will see an athletics track, a full-size indoor football pitch, nine sports halls, a fitness gym and dance studios being created on the former steelworks.

But detailed site investigations have revealed the land sits on 130ft deep caverns and a redundant mine shaft.

The extra work will add around £1m to the cost of the centre, which has already been redesigned because of rising steel costs.

Plans for an outdoor football pitch were scrapped and the size of the athletics hall was reduced in a bid to drive down the final bill earlier this year.

Lizanne McMurrich, head of Community Information and Learning at North Lanarkshire Council, said: "These unforeseen issues were identified after the £29m budget was set.

"There were basements exceeding 40m in depth which needed to be fully excavated and backfilled to ensure stability for the works.

"The extent and depth of the basements varied considerably from the assumptions made.

"No further savings can be incorporated without irrevocably impacting the function and intentions of the facility."

Council chiefs have agreed to fund the budget over-run and will apply to sportscotland in a bid to recover part of the additional sum.

Contractor Balfour Beatty is expected to start work at the end of next month and complete in March 2010.

The Scottish Government, through sportscotland, has contributed £7m to the project, which is also backed by the council and Ravenscraig Limited.

Backers hope the centre will be used as a training facility for the 2012 Olympic Games in London, and the 2014 Commonwealth Games in Glasgow.

The venue will also be the centrepiece of the International Children's Games, hosted by Lanarkshire in 2011.

Work had been due to start on the complex early this summer but was postponed after the redesign was ordered.

It will be the second major project to take shape on the Ravenscraig site following Motherwell College's new £70m base.

The campus is due to be completed in the spring with the first intake of students expected next autumn.