The Panama-flagged vehicle carrier, which is listing at almost 90 degrees, is expected to hit the coast of western France between late Monday and late Tuesday.

The freighter has been adrift since Tuesday. All 22 crew members were airlifted to safety by Spanish helicopters shortly after the crew had sent out distress signals.

A spokesperson for the Dutch company Smit Salvage said the attempt to prevent the ship from grounding will be no easy feat, with high winds and six-meter (20-foot) waves preventing any rescue attempts at the weekend.

"The problem is a combination of several things: the wind, the swell and angle the ship is listing at, which is like climbing a mountain that moves," the spokesperson said.

Maritime prefect Emmanuel De Oliveira told a press conference on Sunday that the operation is "complex and dangerous."

No fuel leak detected

If authorities fail to attach the towline on Monday, plans are reportedly in place to track the vessel until it runs aground in the Landes region and deal with the consequences later.

The Modern Express is carrying 3,600 tons of logs, as well as mechanical diggers and 300 tons of fuel. Maritime authorities said no fuel leak has been detected.

"All available measures to confine and deal with pollution are in the course of being deployed even if the cargo does not present a danger to the environment," they were quoted as saying.

ksb/rg (AP, AFP, dpa)