The government has ordered an independent inquiry into a migrant mass drowning in the English Channel.

At least 27 people including a pregnant woman and three children died when a boat sank in 2021.

Transport Secretary Mark Harper said an inquiry would look at the circumstances of the deaths to give victims’ families the clarity they deserved.

It comes after an investigation into the UK’s deadliest migrant boat incident made two recommendations.

A report by the Marine Accident Investigation Branch (MAIB) said the UK’s emergency response had been hampered by the lack of dedicated aircraft to carry out aerial surveillance of the Dover Strait.

Andrew Moll, chief inspector of marine accidents, said multiple boats had attempted to cross the Dover Straight on the night of the sinking – 24 November – and many had made distress calls.

It had, he said, been “extremely challenging” for the coastguard to understand how many boats were attempting to cross, their locations and levels of distress.

Mr Moll added: “As the pace of dealing with located migrant boats increased, the plight of the stricken craft became masked and, sadly, the victims were not found until spotted by a passing fishing vessel later that day.”

The MAIB’s report also says the Coastguard had insufficient staff at base to correlate the information they were getting from numerous emergency calls made during the night. It said that might have contributed to the wrong assumption that people on board the boat had been rescued by the Border Force.

Mr Moll said the incident had come at a time when the UK’s response to the migrant crisis was evolving, but that the report acknowledged significant changes had been made since.

The MAIB said that by crowding 33 migrants on to the boat, the people who facilitated the attempted crossing had put the occupants at high risk.

The report also found the vessel used by the migrants to make the crossing had been “wholly unsuitable”.

A recommendation has been made for the Maritime and Coastguard Agency and Border Force to develop procedures to ensure effective surveillance of the Dover Strait is possible when aviation assets are unavailable.

And it was also recommended that the Coastguard should work with the French authorities to improve transfer of information during migrant crossings.

Four people are still missing after the sinking and only two survived.

The transport secretary said: “Every day, hundreds of courageous responders from HM Coastguard and other UK agencies, including volunteers, stand ready to respond around the clock to every search and rescue operation involving small boats in the Channel.

“The inquiry I have announced today will allow a thorough and independent investigation into the circumstances of the deaths to take place, further to the MAIB’s report.”

In a statement, the Coastguard said it worked in the most challenging conditions imaginable to save lives and the tragedy was a reminder of the scale of the task it faced.

The French authorities refused to take part in the initial investigation.