Transport Secretary Grant Shapps has written to the firm about the treatment of staff who lost their jobs.
All P&O Ferries contracts across government will be reviewed in response to the way it sacked 800 workers.
Staff have been protesting after many were told without warning by video message on Thursday that it would be “their final day of employment”.
In a letter to the company, Transport Secretary Grant Shapps said he was “deeply concerned” at the move and questioned whether it was legal.
P&O said it was a “last resort” to save the business.
Mr Shapps urged the company to pause the redundancies announced.
Business Secretary Kwasi Kwarteng has also written to the ferry operator’s chairman demanding answers to P&O Ferries’ handling of the redundancies.
P&O Ferries has lost the trust of the British public and has given business a bad name.
The Government wants answers.
My letter to the Chairman of P&O Ferries today 👇🏾 pic.twitter.com/hgMPLOe9vA
— Kwasi Kwarteng (@KwasiKwarteng)
Mr Kwarteng’s letter to chairman Robert Woods claims the company did not follow the correct process in consulting with unions and staff representatives or in notifying him through the Insolvency Service and the Redundancy Payment Service.
The letter says failure to notify is “a criminal offence and can lead to an unlimited fine”.
The Business Secretary also raises the company’s previous application for government support when Covid lockdowns disrupted travel.
“It is particularly depressing that this should happen given the millions of pounds of British taxpayer support P&O companies received from the furlough scheme,” he wrote.
P&O Ferries is owned by DP World which owns ports at London and Southampton.
DP World recently announced £8bn in revenues last year. During the Covid pandemic the company claimed more than £15m in grants and furlough assistance.