COURTICE, Ont. - Hearings into four proposed new nuclear reactors in Ontario are under heavier security today after Greenpeace activists derailed the public review on Tuesday.

Members of the environmental group chained themselves to a table, and while they were eventually arrested and removed from the building, they caused a five-hour delay in the hearings.

They wanted the public hearings suspended while the nuclear crisis in Japan continues, saying there hasn't yet been time to learn the lessons from the dire situation that country is facing.

Ontario Power Generation, the government-owned utility which supplies about 70 per cent of Ontario's electricity, is looking to build up to four new reactors to produce about 4,800 megawatts of power on the shores of Lake Ontario.

Today, people going in to the hearings are being subjected to a thorough search of their bags by police.

Scheduled to present to the joint review panel today are the Canadian Nuclear Safety Commission, Pacific Northwest National Laboratory, Environment Canada, the Ontario Ministry of the Environment and a presentation from OPG on emissions.