The vessel normally works the Hull to Rotterdam route.
Local MP Karl Turner is now at King George Dock near the ferry terminal, where he claims to have seen buses full of workers from overseas who are ready to take over operations on the Pride of Hull.
It has been reported that 800 officers and crew employed by P&O have been told they have lost their jobs and that an agency will be contracted to provide staff in future.
The severance is apparently due to P&O needing to make 'immediate' changes to its operations to ensure viability and survival.
Mr Turner claims a 'sit-in' is now taking place with the support of maritime union the RMT and that the seafarers will not leave the vessel to allow the new crew on board.
He also said the captain had said they would refuse to allow police officers to board the ship.
He tweeted: "New foreign crew waiting to board the Pride of Hull on King George Dock. RMT sitting in on board the vessel. They will not be boarding her. We understand that both current officers and ratings are to be sacked.
"I’m hearing that the captain of the Pride of Hull will refuse to allow the police to board the vessel if P&O ask them to do so. The official sit-in of the ship is supported by both officers' and rating's trade unions."
P&O have yet to make further public announcements about the company's future.
Last year P&O axed the Hull to Zeebrugge service and put the Pride of York ferry up for sale.
s a separate business owned by Carnival UK.