TORONTO - It's proving harder than anticipated to convince the companies wanting to build new nuclear reactors in Ontario to accept the risks associated with delays.

The province is extending a Dec. 31 deadline for the final bid proposals for two new reactors to be built at Darlington until next spring.

Energy Minister George Smitherman blames the delay on the province's attempt to get private-sector bidders to agree to pay for delays and overruns caused by factors under their control.

Smitherman says the issues "are intensely discussed and negotiated point by point by point," so he had to extend the bid deadline.

NDP Leader Howard Hampton says taxpayers always end up on the hook for cost overruns on new nuclear plants because private companies won't accept the risk.

The Progressive Conservatives say the Liberals should be speeding up the process, but Smitherman says delays on such a huge project are to be expected.

Ontario plans to build two new reactors at the site of the existing Darlington plant so nuclear power continues to generate 50 per cent of the province's electricity.

Privately run Bruce Power announced plans last week to conduct an environmental assessment for new reactors to be built on the shores of Lake Erie at Nanticoke, prompting Smitherman to accuse the company of trying to influence government policy.

Smitherman insisted there are no plans for any more reactors to be built other than the two new units at Darlington, and he said Bruce has no approvals to construct any new nuclear plants.