Four Vietnamese nationals have been arrested following an investigation into alleged people smugglers advertising small boats crossings on Facebook.
The joint UK-French investigation alleges the group shared posts aimed at the Vietnamese community and charged migrants thousands of pounds to make the crossing.
Officers arrested a 23-year-old woman at an address in Heathfield Road in Croydon, south London, a 64-year-old man at an address in Abinger Grove, London and a man, 34, in Grasmere Street, Leicester on Monday, the National Crime Agency (NCA) said.
The older man is thought to have acted as a driver, collecting migrants who arrived on small boats and on at least one occasion bringing them back to the Croydon address.
They were held on suspicion of assisting unlawful immigration and questioned by officers.
All three were charged and appeared at Croydon Magistrates Court on Tuesday, the NCA said.
A 25-year-old man was also arrested at the same address in Croydon on Monday on a warrant issued by the French authorities.
He will now face extradition proceedings after he was allegedly involved in people smuggling and drug offences.
A further 12 individuals suspected of being linked to the same people smuggling network have also been arrested in Paris, France.
Home Secretary James Cleverly said: “We are using every possible lever at our disposal to crack down on people smugglers and break their supply chains.
“Just last week, we signed a new agreement with Vietnam, strengthening our cooperation on illegal migration.
“Together with law enforcement agencies such as the NCA, our French partners, and other countries like Vietnam, we are committed to dismantling the criminal gangs who are trying to turn a profit by abusing our borders.”
Chris Farrimond, NCA director of threat leadership, said: “Vietnamese nationals now make up a large number of those we see arriving on small boats.
“We allege this group were advertising their crossing services on social media to encourage others from their country to make the same treacherous journey.
“The NCA is continuing our work with partners and has had thousands of social media pages and posts advertising organised immigration crime services removed from platforms.”
Mr Farrimond added: “Tackling organised immigration crime is a priority for the National Crime Agency and our investigation continues to target people smugglers both in the UK and overseas at every step of the route.”