Canadian and U.S. Coast Guard cutters are busy clearing ice in the St. Clair River and Lake Huron after three freighters had to be escorted through thick pack ice over the weekend.

The freighters were heading down to the St. Clair River from Lake Huron, with ice blocking their way.

Larger vessels, including the Canadian cutter, The Griffon, will be working on Lake Huron on Monday, while smaller cutters will be making sure the pieces don't jam up and cause flooding in the St. Clair River.

On Sunday night, about  three kilometres of ice broke free from the lake and made its way down the river, said  Andy Maillet, supervisor of ice breaking operations for the Canadian Coast Guard in Sarnia.

"Now we have considerable amount of ice in the river and it's all flowing down. But it is jammed up at the northern end — north of the Bluewater Bridge," said Maillet.