The incident occurred in the closing stages of Thursday morning's FP1 session, as Nico Rosberg's Mercedes lifted up the cover at, which then flew into Button's McLaren behind at Ste Devote.

It damaged Button's front wing, suspension and brake intake, as well as necessitating a change of floor in time for second practice.

"It's never acceptable when there is an incident like this," said Alonso when asked about what happened to his McLaren teammate.

"It's something that we didn't take care of enough before practice in terms of circuit checks, in terms of the FIA, and everyone has to go into the details to make sure everything is safe to run."

The Spaniard added the incident was a reminder that F1 must proceed with plans to introduce some form of extra protection for drivers.

"This is another reason to come back to the canopy idea," he said.

"Let's make sure that between all of us, between the sport in general, we minimise the risks that are always there."

Button says low impact "lucky"

Speaking about the incident, Button said he felt he was lucky that the drain cover struck the car fairly low down on his McLaren in what he described as an "extremely dangerous" situation.

“Normally it’s a great place, safety-wise they’ve got a good record," he said. "But today we had the drain cover that moved, which we can’t have.

"They have to stay down, we have enough dangers. A drain cover lifting in the air with an open-top car is extremely dangerous.

"We were lucky in a way it just damaged the car, it stayed quite low to the ground, which was good."

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