A pregnant woman was among 31 migrants who had to be rescued after attempting to cross the Channel overnight.
French coastguard officers rescued the migrants after the engine of one small boat cut out and another began to take in water, authorities in France said on Sunday.
Several attempted crossings have been intercepted recently, including on Boxing Day when 49 suspected migrants from Iran, Iraq and Afghanistan were escorted to British shores after a search and rescue operation.
In the latest incident, the Home Office said, French coastguard officers picked up 11 people, including two young children, after the engine failed in their small boat off the coast near Calais in the early hours of Sunday.
Another 20, including the pregnant woman, were later rescued by the same patrol boat further along the French coast near Dunkirk after their small boat took in water, local authorities said in a statement.
A number of those rescued were being treated for hypothermia, with all 31 taken to the French port where they were met by medics and border police.
A third vessel carrying a group of 10 men and one woman claiming to be from Iran was also intercepted off the coast of Kent at 5.34am. HM Coastguard said two Border Force boats brought the migrants to shore. They were being medically assessed before being transferred to immigration officials for interviews.
The figure for the number of suspected migrants to reach the UK this year in small boats is believed to be more than 1,800 with 79 people picked up on 4 December and 69 taken in on 17 December.
The rescues reflect a renewed effort to try to stop migrant crossings. The Home Office said last week that patrols on French beaches had doubled and drones, specialist vehicles and detection equipment had been deployed.
In a statement they said: “Illegal migration is a criminal activity. Those who seek to come to the UK unlawfully and the ruthless criminals who facilitate journeys are all breaking the law and endangering lives.
“We will always ensure we have the right resources in place to keep our border secure. A 42-metre Border Force cutter and two coastal patrol vessels are patrolling the Channel and we are monitoring the situation closely over the Christmas and new year period.”
Since January 2019, more than 125 migrants who entered the UK illegally via small boats have been returned to Europe, according to government figures.
