Most of scandal-hit P&O Ferries’ services remain suspended - three weeks on from its mass sacking of 800 seafarers.
The firm also announced that sailings on its key Dover to Calais route were cancelled this weekend, threatening to impact those trying to get to abroad for the Easter getaway.
Of P&O’s eight ferries that were affected by the axing of crew, and replacement by agency workers, just one has been cleared to sail.
Two others have been detained by the Maritime and Coastguard Agency, with the remainder awaiting inspections.
The MCA said: “There are no further inspections of P&O Ferries at the moment and we will reinspect at the appropriate time.”
Two other vessels - the Pride of Rotterdam and the Norbank ferry between Liverpool and Dublin - were not impacted.
P&O Ferries says it will provide a full refund to anyone who was due to travel on its Dover to Calais route this weekend.
On its Twitter feed, it added: “We will also pay back the difference in cost between your P&O Ferries ticket and your new booking with another operator.”
A spokesperson said: “From this weekend, P&O Ferries are getting ready to resume services across a number of vital routes.
“P&O has been working closely with regulators to ensure our ships are safe to sail. “P&O is looking forward to welcoming back vital services and we expect to have two of our vessels ready to sail on the Dover-Calais route by next week, subject to regulatory signoff, namely both the Pride of Kent and Spirit of Britain between Dover-Calais.
“P&O are also expecting to be able to sail both the European Causeway which runs between Larne and Cairnryan; and the Pride of Hull, which runs services between Hull and Rotterdam.”
A criminal investigation has been launched into P&O Ferries’ sacking of 800 crew, as politicians also called for a public inquiry into the scandal.
The Insolvency Service said last week it had “initiated both formal and criminal and civil investigations”.
Peter Hebblethwaite, boss of P&O Ferries, has already admitted the firm knowingly broke the law by not consulting with unions before the sackings last month.
