Ferries from Dover have been cancelled because of the strike

SeaFrance cancelled all sailings but P&O only stopped services when its freight ship was forced to turn back.

The company was told it was too dangerous to try to land passengers or freight because pickets were lighting fires on the dock using old tyres.

Kent Police closed the coastbound M20 between junctions 10 and 12 on Thursday afternoon for use as a lorry park.

The rest of P&O's passenger fleet was still in Dover.

'Enormous costs'

However, SpeedFerries and Norfolk Line, which operate between Dover and Dunkirk and Boulogne, said both routes were operating normally.

The blockade in Calais by SeaFrance workers, which is over new ferry employment regulations being introduced in France, was lifted on Thursday evening.

Tourists and lorries stranded by the dispute were being taken across the Channel via Eurotunnel shuttle services.

Geoff Dossiter, external affairs director of the Kent-based Freight Transport Association, said the strikes, which were coming at monthly intervals, were causing "enormous costs and inconvenience" to companies, drivers and deliveries.

'Tiresome behaviour'

He urged France "to get a grip on this tiresome and expensive behaviour and act to properly police its ports and allow the free flow of trade and passengers."

The action also caused minor delays at other French ports, although Boulogne and Dunkirk were open as normal.

Ferry services between Dover and Calais were initially disrupted on Wednesday by wildcat strike action and technical problems.

The Dover Harbour Board said strikes in France are in response to laws being discussed in the French parliament.