A single boat that crossed the English Channel at the weekend had 105 migrants on board, with the average number of people crammed into each vessel rising.
In a victory for the UK government, overall numbers making the perilous journey have fallen in recent months.
But that has been offset by increased numbers boarding each boat, which has been attributed to actions by the French authorities in intercepting boats and disrupting the supply chain for the vessels' components. That has forced smugglers to cram more migrants onto "mega dinghies" to maintain their profits.
Between January and June this year, the number of migrants crossing to the UK from France was 11,884, down from a record 19,982 in the previous six months.
Last year, The National reported the average number of asylum seekers per boat per day sometimes reached 80, but that has risen significantly.
The Home Office publishes statistics on the number of migrants who arrive each day and the number of boats; however, it does not publish the number of migrants on each vessel.
In the first six months of 2025 the overall daily average per boat was 58, which has risen to 65 for the same period this year.
Recent days have seen boats with 94 and 105 people on board, the only crossings on those days. In November, it was reported that 125 people sailed in one boat, but that could not be confirmed due to several other crossings taking place on the same day.
The larger numbers have in the past been blamed for deaths as more cram on to the boats, increasing the risk of suffocation or drowning.
France and Britain signed a £660 million ($891 million) three-year agreement in April to prevent migrants reaching the UK. The agreement, which has now come into force, includes stationing riot police on beaches.
"Every time the UK and French Governments have announced another border security initiative, it has just made Channel crossings even more dangerous," Charlotte Khan, head of advocacy and public affairs at the refugee charity Care4Calais, told The National.
"The number of people travelling on single boats has been on an upward trajectory for years, and that shows no sign of ending whilst the two governments obsess over failing deterrence policies.
"The UK government could end crossings, and save lives overnight by opening real, accessible safe routes for refugees to claim asylum."
Outgoing Prime Minister Keir Starmer had made tackling small boats a priority, as part of an effort to reduce migration in general.
Home Secretary Shabana Mahmood has indicated a toughening of Britain’s stance on refugees. She has been inspired by the hard-line approach taken by Denmark, whose government is led by Prime Minister Mette Frederiksen, a fellow centre-left politician.
Under a proposed new law she introduced this week, people granted asylum in the UK face having to pay back about £10,000 towards the cost of their accommodation and support once they start earning.
The Immigration and Asylum Bill would also restrict the ability of migrants in the UK illegally to use Article 8 of the European Convention on Human Rights, which protects the right to family life. Critics say the law has been abused to allow people with no connection to Britain, or who travelled through other countries before declaring asylum, to remain in the country.
Ms Mahmood has also proposed refugees will have to live in the UK for 20 years before they can settle permanently.
A Home Office representative said: “This Government is bearing down on small boat crossings, with removals of small boat migrants at record levels and asylum claims down by 12 per cent.
“The Home Secretary has signed a landmark new deal with France to boost enforcement action on beaches and put people smugglers behind bars. This builds on joint work that has stopped over 44,000 attempted crossings since the election."
