HALIFAX - A sensitive marine area teeming with fish off Nova Scotia's southwest coast would be protected from commercial offshore drilling indefinitely under legislation introduced Wednesday by the provincial government.

Oil and gas drilling would not occur on Georges Bank unless science produced evidence indicating it would be safe to proceed, Energy Minister Bill Estabrooks said. Even then, Estabrooks said it would take a public hearing and a vote in the legislature to lift the moratorium.

"It's just not worth the risk to drill in an area this important to Nova Scotians," he told a news conference.

Ottawa and the provincial government agreed in May to extend a drilling ban that was set to expire in 2012 for another three years to allow time for further study. The ban has been in place since 1988.

"Rather than continue this debate every few years, our legislation will provide certainty about our intentions around Georges Bank," Estabrooks said.

Georges Bank is a rich fishing area known for its abundance of haddock, halibut and scallops. Its vast, shallow seas are also home to endangered species of whales and turtles that migrate through its nutrient-rich waters.

The area, about 100 kilometres off the coast, is also thought to contain large quantities of natural gas.

The province's move was hailed by Norigs, a coalition of fishermen, seafood processors and environmentalists who had been advocating a permanent ban on oil and gas development in the region.

"Finally we are getting something that is a lot more permanent than what we've had in the past," said Claude d'Entremont, a spokesman for the group.

D'Entremont, of Inshore Fisheries Ltd. in Lower West Pubnico, N.S., said the ban is important to a region that benefits from a $200 million fishery on Georges Bank.

"Our company alone hires up to 100 people and most of our fish is from Georges Bank," he said.

The bill does not prohibit research work in the area, including seismic testing intended to understand the seabed's geology. D'Entremont expressed concern about that, saying he was worried about the potential effects of any seismic testing in the area.

Earlier this year, U.S. officials said no drilling licenses would be considered on the American side of Georges Bank, effectively extending a ban there until 2017.

"We want to work in co-operation with both the U.S. and the federal government, but first and foremost ... we have a responsibility to make sure that we are taking the lead on this," said Estabrooks.

Although the opposition Liberals and Conservatives welcomed the legislation as an important step, they wondered why a definitive ban isn't in place.

Liberal Andrew Younger noted that any changes would simply require a resolution of the legislature.

"We think the act should be structured so that it would have to be repealed in its entirety by the legislature, he said.

Conservative Chris d'Entremont said the door is still open for future oil and gas exploration.

"It doesn't provide the protection that we need on Georges Bank, which is an outright ban forever and a day," said d'Entremont.

The province shares jurisdiction over Georges Bank with the federal government.