SYDNEY, N.S. -- A heavy-duty icebreaker has moved into the strait between Cape Breton and the island Newfoundland, where thick pack ice is slowing the ferries that serve the two provinces.

Marine Atlantic spokesman Darrell Mercer says the Canadian Coast Guard ship Amundsen is on standby in case any ferries get stuck in the Cabot Strait.

Mercer says shifting winds are expected to force more pack ice into the strait this weekend, causing a buildup of pressure.

He says the ice is particularly thick near the Nova Scotia side.

At this time of year, the ferries operate between North Sydney, N.S., and Port aux Basques, N.L., a 180-kilometre voyage.