SeaFrance unions staging a walkout in Calais over the company's plan to cut more than 500 jobs have prevented a P&O ferry from berthing at the port.

Chris Laming, spokesman for P&O, has confirmed the Pride of Burgundy has been unsuccessfully attempting to berth in France as around 300 strikers take the industrial action.

Operation Stack is in place on the M20 and all ferry services are suspended from the Port of Dover.

The Pride of Burgundy has been turned around to head back to Dover.

SeaFrance would not comment on the development.

SeaFrance staff and management are due to meet on Monday to continue their talks on the future of the company.

The employee consultative committee is expected to give its final views on the company's redundancy plan which has changed since it was first announced in February, but involves shedding hundreds of jobs and some of the fleet of cross-Channel ships.

It is understood that the CFDT union has called the strike to protest at what it describes as the company's "inflexibility".

Union officials say that what is being proposed is far more severe than is needed to address SeaFrance's financial situation.

The union wants the French government to appoint a mediator to help resolve the dispute.

But SeaFrance say that any further delay in implementing the redundancy plan will increase the risk of the company failing to obtain the financial support of its parent, French national rail operator SNCF, and therefore becoming insolvent.

A notice on the SeaFrance website on Thursday read: "We regret to inform you that our sailings will be suspended from 07:00 hours on Friday 16 October until 08:30 hours on Saturday 17 October. For further information please call 0871 222 0711.

"We anticipate that all sailings will return to normal operation from 08:30 on Saturday."

• For more information visit www.seafrance.com