A man and a woman have been arrested on suspicion of facilitating illegal immigration by supplying small boats to people smugglers.
It follows an arrest in October as part of a National Crime Agency (NCA) investigation into a criminal network.
Officers believe the group was involved in buying at least six vessels, which were then moved to France or Belgium.
Three of those boats were found back in England, having carried migrants across the Channel.
One was found in St Margaret's Bay in Kent on 2 September, a day in which about 400 people reached the UK using small boats.
'Expect to be pursued'
An 18-year-old Lithuanian national woman was detained at an address in The Cheviots, Hastings, by NCA officers.
A 20-year-old Syrian man was also arrested at an address in London Road, St Leonards-on-Sea.
They are both now being questioned.
A 30-year-old man in Battle Road, Hastings, was apprehended last month and released under investigation.
NCA Branch Commander Matt Rivers said: "This operation demonstrates that not only are we going after the people smugglers themselves, but we are also targeting their business model by targeting their suppliers.
"These Channel crossings are incredibly dangerous, as shown by recent and historic mass fatalities, and the criminals who organise them are simply exploiting migrants by taking their money and then putting them in life-threatening situations.
"People who willingly make that possible, whether it be through providing social media advertising, financial services or supplying boats, can expect to be pursued by the NCA and held accountable."