More than 100 migrants stormed the Calais ferry terminal in a coordinated push to board a Dover-bound ferry, forcing the authorities to delay its departure while they rounded them up yesterday.

About half of the migrants managed to scramble onto the ferry and conceal themselves on board. Two fell into the sea and were rescued.

French police arrested at least 46 migrants but were continuing to search the vessel, where it was believed several were hiding.

Some were discovered on an external catwalk attached to the ship’s funnel and firefighters were trying to persuade them to come down, according to Jean-Philippe Vennin, a Prefecture official.

“Firemen managed to get close to them but did not succeed in talking them down, so a second attempt is underway,” Mr Vennine said yesterday afternoon.

The men broke into the highly protected ferry port at just after 8.30pm on Saturday soon after the Danish-operated DFDS Seaways ferry arrived from Dover carrying 211 passengers and 75 crew members.

The migrants used a maintenance ladder to clamber aboard the ferry at high tide, according to Mr Vennin. “Two fell into the sea and were quickly rescued by firemen,” he said.

Police oversaw the offloading of all the cars and lorries arriving from Britain before carrying out a top-to-bottom search of the vessel. It was moved during the night to avoid further delays while police searched it.