Concern for the safety of 500 employees has stopped work on the controversial $1.3 billion Strategic Sewage Disposal Scheme. Experts have been called in to try to halt the continued seepage of water into tunnels which is threatening the lives of on-site workers. The Drainage Services Department said yesterday work on all six sections of the tunnel had stopped and the unresolved problem could push back the project's mid-1997 completion date. The stoppage followed a dispute between contractors and the Government over safety fears for the workers after ground water seeped into a section of the tunnel near Tseung Kwan O. Deputy Director of Drainage Services Chung Kwok-leung said British experts believed work could continue safely in the tunnels and talks to resolve differences were under way. 'Water problems in tunnels so deep are a common geological phenomenon all engineers have to face, but they think they have problems with it and now we must sit down and work out the way forward,' Mr Chung said. Legislators fear the dispute will increase costs. Democrat Dr John Tse Wing-ling said geological assessments of the rock before work began might have been insufficient. 'The whole thing has been a great disappointment and the public should not have to foot the bill for maladministration,' Dr Tse said. Mr Chung admitted contractors could claim for extra costs should problems hold up projects. The department paid the firm an extra $150 million in March to accelerate construction after delays caused to other contractors by poor ground conditions in the project's early stages. Part of the extra money went into buying a fifth tunnel-boring machine to speed up work. Contractors have also complained of manpower shortages for the project, which involves a 25-kilometre sewerage network linking collection points on Hong Kong Island and Kowloon to a treatment centre situated on Stonecutters Island. Outfalls will eventually dump treated waste in western sections of Victoria Harbour.