MACKINAW CITY, MICH. -- Michigan's attorney general on Monday asked a judge to shut down a pipeline in the Great Lakes after an energy company discovered that an anchor support had shifted deep below the surface.

Enbridge Inc. insists the Line 5 pipeline itself was not damaged, and the company resumed the flow of oil and natural gas liquids in the west leg of the twin system Saturday. The east line, where the anchor support assembly had moved, remains closed in the Straits of Mackinac.

But state attorneys said both should be turned off until an independent review is conducted. They asked for a restraining order and an injunction as part of ongoing litigation between Enbridge and Attorney General Dana Nessel, who wants Line 5 permanently shut down.

"Enbridge's prevention and detection measures have failed to prevent or detect the source of this damage, and that failure has created a risk of irreparable harm to the Great Lakes," state attorneys said.

Line 5 carries oil and natural gas liquids used in propane from Superior, Wisconsin, to Sarnia, Ontario. A four-mile (6.4-kilometre) segment divides into two pipes that lie on the bottom of the straits, which connect Lake Huron and Lake Michigan between Michigan's Upper and Lower peninsulas.

Enbridge said it would vigorously oppose Nessel's legal moves. The company said it has kept federal pipeline regulators informed of the situation since last week.

"I have directed the responsible individuals at Enbridge to ensure we provide regular and fulsome briefings to state officials and discuss current plans with your administration and with you personally, if desired," President Al Monaco said in a Sunday letter to Gov. Gretchen Whitmer.

But Whitmer said Enbridge restarted the west leg of Line 5 without sharing enough information about the incident. She called it a "brazen disregard for the people of Michigan" and the safety of the Great Lakes.

Enbridge wants to ultimately put the twin pipes in a tunnel to protect them. The project was approved in 2018 before Whitmer and Nessel took office.

Line 5 delivers 65% of the propane that heats Upper Peninsula homes and 55% of Michigan's propane needs, according to Enbridge. It has been operating since 1953.