Icebreakers and helicopters have been deployed off Canada's eastern seaboard to help free some 600 seal hunters who have become trapped in pack ice, Canadian news reports said Thursday. Some of the 100 hunting vessels have been stuck for up to a week in the ice off the north-eastern coast of Newfoundland to the south of Labrador, dpa quoted the Globe and Mail newpaper as reporting. Fuel, drinking water and food were running dangerously low on some of the ships as heavy weather hampered the rescue efforts of the Canadian Coast Guard. Weather conditions were so harsh that an icebreaker belonging to the coast guard that was attempting to reach the trapped vessels itself became trapped in the pack ice. "I've talked to a lot of sealers and they've got holes punched in their new boats and they're taking on water," Frank Pinhorn, executive director of the Canadian Sealers' Association, said. Some 15 ships were in "extreme difficulties," Canadian Coast Guard spokesman Captain Brian Penney said as the crushing pack ice was threatening to breach the sides of their vessels and sink them. In some cases, crews had already abandoned their vessels and were awaiting rescue on top of the ice. "We've been at this around the clock," Penney told the Globe and Mail. "It's tiring, time-consuming, and it's a job that we have to do and we keep trying. But it's very long hours for our captains and our crews. "They're putting a lot of effort into pulling them out. But the sheer numbers, it's a very, very slow process."