Two children were among a group of 18 Albanians and two British people rescued from the English Channel after their inflatable boat began to sink.
The UK Coastguard received a call for assistance just off the coast of Dymchurch in Kent at 11.40pm on Saturday. A search-and-rescue helicopter was deployed as well as lifeboats and coastguard rescue teams.
The rhib (rigid-hulled inflatable boat), with 20 people on board, was found at 2am and the matter was handed over to Border Force.
It has been reported the people on board had alerted their families in Calais, who raised the alarm with the French authorities.
The incident has sparked fears that tragedies seen in Greece or Italy will start to occur in the Channel.
President of the French coastguard, Bernard Barron, told Sky News: "It's starting to become a very similar situation to that seen in the Mediterranean and my biggest fear is that the same kind of tragedies we see in Greece or Italy will start to repeat in the Channel."
He added that smugglers had found a new way of bringing migrants into the country after it had become "virtually impossible" for them to enter via the Channel Tunnel or on ferries.
"They operate across the length of both the French and Belgian coastlines, between Ostend and into Normandy, finding new positions from where they can send their clients - the migrants - towards England."
Mr Barron said that even though the smugglers were being given large sums of money, there were not providing suitable transport for a "sea filled with danger, with strong currents, storms and heavy traffic of larger vessels".
A Home Office spokesman confirmed woman and two children were aboard the boat that was rescued on Saturday.
He added that a second vessel, believed to be linked to the inflatable that got into trouble, was discovered on the beach at Dymchurch.
The spokesman said: "A total of 20 people were picked up in a search and rescue operation. 18 were Albanian, and two were British. There was one woman, and two minors.
"They were taken to Dover and are currently being interviewed by Border Force officers."
Councillor Mary Lawes, Ukip group leader on Shepway District Council, said she was concerned for the security of the region as well as the safety of migrants seeking to cross the Channel in unsafe boats.
She said: "We are not doing enough to control our coastline, the Government has to address border controls, something has to be done to protect these people from harm and our borders."
David Monk, Conservative leader of the local authority, said he believed high levels of surveillance in the English Channel would mean most boats crossing the channel would be identified.
He added: "I am pretty sure our security is good. I cannot recall a previous incident but this should act as a warning to the authorities to be even more vigilant."
The incident comes after 17 suspected Albanian migrants and a British man wanted on suspicion of murder in Spain were detained after a catamaran arrived at Chichester Marina in West Sussex on Tuesday.
The 55-year-old man, who was the subject of a European Arrest Warrant, was also detained on suspicion of facilitating illegal immigration while the 17 Albanian men were held on suspicion of entering the UK illegally.
The Albanians have been detained pending Home Office consideration of their cases. Also last month, two Iranian men were found floating in an ill-equipped dinghy in the English Channel.
The National Crime Agency recently revealed migrants trying to reach the UK are paying smuggling gangs up to £13,500 for their journey.