P&O Ferries’ plan to restart Dover-Calais crossings in time for Easter is under threat as a row escalates between the Government and the Dubai-owned operator.

Whitehall sources said that P&O vessels could remain moored in ports until May after failing to pass stringent safety checks.

Further delays would raise the stakes in a dispute between Grant Shapps, the Transport Secretary, and the operator.

P&O said last week that it would restart sailings between Dover and Calais in time for Easter. It admitted this timetable would be “subject to regulatory sign off”.

The company has three ferries moored in Dover and another in a dry dock at the Kent port.

Inspections by the Maritime and Coastguard Agency (MCA), a division of the Department for Transport, typically take officials two days to complete. This means it is unlikely that P&O’s vessels would be up and running for Easter even if they were presented to officials on Monday.

Late on Friday, the MCA released the European Causeway after detaining the vessel in its port in Northern Ireland last month.

A spokeman for the MCA said: “There are no further inspections of P&O Ferries planned for the weekend.” 

P&O has already accused the MCA of “an unprecedented level of rigour” over its inspections. The authority responded: “We inspect without fear or favour.”

One of the ferries at Dover, the Pride of Kent, was detained by officials after failing safety checks 10 days ago. One Whitehall source said that this was a significant failing, and one that would take some time to rectify.

“If your whole safety management system is down the pan, that [Easter] is really optimistic,” they said.