A former UK Border Force chief says he fears further loss of life if migrants continue to cross the Channel.
On Monday two men in a boat were rescued off the coast of Harwich, Essex, but the search for a third has been called off.
The Home Office would not confirm if it believed the man had died.
Retired chief immigration officer Kevin Saunders believes the men set off from Dunkirk in France and were likely blown off-course.
"If people attempt to come across the Channel at this time of year, there are going to be a lot more deaths," he said.
"I wouldn't want to go across the Channel on a ferry, it's too rough. So coming across on a small dinghy is very, very dangerous."
He said French officials had been "quite successful" in stopping migrants crossing from Calais but it meant people were now attempting longer, more dangerous routes from elsewhere in France.
The Maritime and Coastguard Agency (MCA) said a helicopter and a plane were involved in the search and it is understood RNLI lifeboats were launched from Harwich, Frinton and Walton.
The Home Office said two Somali nationals were being processed within the immigration rules and an "extensive" search and rescue operation for a third man concluded at about 14:00 BST on Tuesday.
A spokesperson said: "We are determined to do everything we can to prevent people dying in the Channel.
"The government's new plan for immigration and ongoing work with the French government will help us crack down on organised criminals and reform the asylum system to deter people from attempting these deadly crossings."
More than 19,400 people have made the crossing from France to England in small boats so far this year, compared to just over 8,460 in 2020, according to Home Office figures.
In July, the UK promised France £54m to boost police patrols at its beaches.