Voters in a sparsely populated district of rural Alaska have narrowly passed a ballot initiative that could block development of the controversial Pebble Mine, local officials said late Monday.

Voters in the Lake and Peninsula Borough of southwestern Alaska passed the ordinance by a 280-246 vote, according to preliminary election results released by the borough clerk.

The election was Oct. 4, but all local elections in the borough are conducted by mail ballot, and officials had to wait for mail delivery from outlying villages.

The Save Our Salmon initiative would amend borough development code to automatically deny local permits to any large-scale resource extraction project that would damage or degrade salmon habitat.

The ordinance was aimed at the Pebble project, a proposed open-pit copper and gold mine that would be among the largest in the world. The Pebble Ltd. Partnership, which is pursuing the mine, is jointly owned by Anglo American and a Canadian junior mining company, Northern Dynasty Minerals Ltd.

The mine has been a contentious issue in Alaska.

Critics say it would spoil important habitat upstream from Bristol Bay, site of the largest sockeye salmon runs in the world. The area where the mine would be built is close to national parks and unspoiled wildlife habitat, and the mine is opposed by commercial fishermen, sport fishermen, Native subsistence fishermen and environmentalists.

But mine supporters say the project is needed to bring jobs and economic development to a struggling region of the state. Supporters say residents in the region should use the mine to diversify an economy that is too dependent on salmon fishing.

A sponsor of the initiative said its passage shows that local residents reject the Pebble project.

The results of this election prove once and for all that Native Alaskans will not allow important salmon habitat to be destroyed for the sake of enriching foreign corporations, Jackie Hobson, a local resident and initiative sponsor, said in a statement released Monday night. Local residents have made their opposition to the development of the Pebble Mine crystal clear with the passage of the SOS Initiative.

The Pebble Partnership, which unsuccessfully sued the borough to remove the initiative from the ballot, said in a statement that it will continue litigation to prevent the measure from going into effect.

This was a very close election and we are appreciative of the many voters from the Lake and Peninsula Borough who dedicated time to understand the true risks presented by this ill-conceived ordinance and the very real impacts it could have regionally, the statement said.

The State of Alaska has stated that this ordinance is unenforceable as a matter of law and will not withstand the legal challenge that continues in Alaska's Superior court next month. We agree and will continue our legal challenge for the reasons we have stated throughout this process. Our view remains that this change in the borough code is not legal, the statement said.