Most of the officers on board Irish Ferries vessels stranded in Welsh ports for the last six days were expected to be relieved by Irish colleagues from the company late last night.
However, four engineering officers who have been barricaded in the control room of the Isle of Inishmore at Pembroke port last night said that they would continue with their protest.
Crews on Irish Ferries vessels are regularly relieved by colleagues in the company to allow for a continuity of service.
The move by the company yesterday to bring relief crews from Ireland to Wales came just hours after the company withdrew controversial security personnel which it had placed on board the vessels last Thursday.
Ratings on The Isle of Inishmore and The Ulysses in Holyhead, are scheduled to be relieved today.
Replacement crews consisting of seamen from Eastern Europe, whom the company wants to take over the running of the ship also remain on board.
The convenor of the International Transport Federation for Britain and Ireland, Norrie McVicar, said last night that he had been informed that the Eastern European crew on The Isle of Inishmore were now wearing Irish Ferries uniforms.
A spokesman for the company declined to comment on the move to bring in the relief crews.
The departure of the security personnel from The Isle of Inishmore at Pembroke came at lunch-time yesterday.
The men were transported by the company from the port in a three-vehicle convoy. However, a couple of miles away in the town of Pembroke the convoy was confronted by inspectors from the International Transport Federation in a carpark as the men were to be transferred to a larger coach.
An official of Irish Ferries called the police and complained about the inspectors following the convoy. Some of the security men pulled hoods over their heads to shield their identities from photographers.
News of the departure of the security personnel was given to crew on the vessel at around noon in a statement from company chief, Eamonn Rothwell.
There were seven or eight young men in the minibus with three or four in each of the people carriers. Some of the men wore hooded tops.
The vehicles drove out of the port and headed along country roads to the town of Pembroke, two miles away.
The convoy circled the town and ended up in a carpark where it appeared the men would be transferred to a coach.
As the inspectors drew near an official of Irish Ferries spoke to the coach driver and waved him off.
The official then called the police as the inspectors and a photographer working for The Irish Times took pictures of the men. As the police officers spoke to the inspectors and journalists, the convoy drove off.
Meanwhile, the situation on The Isle of Inishmore remained deadlocked last night.
One of the engineers in the control room John Curry said that they would remain barricaded in the area until advised to leave by their trade union, Siptu, in Dublin. Many key functions of the ship are managed from the control room and while the engineers remain there the vessel cannot move.
In a separate development the British union representing ships officers, Numast, called for an inquiry into how security personnel had been "smuggled" onto Irish ferries vessels last week.