P&O Ferries is planning to restart operations between Dover and Calais in the coming days amid accusations it attempted to further reduce the wages of its seafarers.
According to PA, the firm is selling tickets for cross-Channel sailings on its ship Spirit of Britain, with the first departure for freight customers at 4.25am on Wednesday from the Kent port.
However, reports suggest P&O does not anticipate carrying tourists until early next week.
It will be the first time it has operated a ferry on the route since it unexpectedly sacked 800 workers without notice in March, replacing them with cheaper agency staff in a bid to shore up its finances.
The agency workers will be earning an average of £5.50 ($7) per hour, less than the UK minimum wage, which has provoked anger from trade unions and politicians.
The company said at the time it had made a loss of £100m year-on-year, and that its survival was dependent on making “swift and significant changes now”.
Spirit of Britain was detained by the Maritime and Coastguard Agency on 12 April after safety issues were found. However, was cleared to sail on Friday.
It comes as Rail, Maritime and Transport (RMT) union general secretary Mick Lynch has claimed that P&O Ferries has been "prevented from further cutting the pay of vulnerable agency crew" by "pressure from RMT seafarers".
Watch: Criminal inquiry launched into P&O Ferries sackings
But the firm insisted no agency workers were asked to take a pay cut.
“There are no depths to which P&O and their Dubai owners at DP World will not sink to extract the maximum profit from ferry crews operating our vital maritime supply chains,” Lynch said.
“This is underlined by the fact that, despite this U-turn, P&O are still only paying barely half of the UK minimum wage of £9.50 per hour.”
He added: “Ultimately, staffing ships with super-exploited agency staff is not just morally wrong, it undercuts those remaining ferry operators who do abide by union rates of pay and conditions, and undermines passenger safety.
“The only way out of this latest crisis at the ferry operator is for the government to take over the running of P&O vessels and reinstate directly employed staff on union rates of pay.”
A spokesman for P&O Ferries said: “No agency seafarers were asked to accept reduced wages.”