British police said on Wednesday they had arrested three men over the deaths of five migrants including a child who died attempting to cross the Channel from France the day before.

The deaths occurred when a small overcrowded boat carrying 112 people set out to cross one of the busiest shipping lanes in the world and panic took hold among the passengers not far from the shore.

Rescuers picked up about 50 people, with four taken to hospital, but others stayed on the boat, determined to get to Britain.

Three men, two Sudanese nationals aged 22 and 19, and a South Sudan national aged 22, were detained on Tuesday night on suspicion of facilitating illegal immigration and entering the UK illegally, the National Crime Agency (NCA) said.

"This tragic incident once again demonstrates the threat to life posed by these crossings and bring into focus why it is so important to target the criminal gangs involved in organising them," said NCA Deputy Director of investigations Craig Turner.

"We will do all we can with partners in the UK and France to secure evidence, identify those responsible for this event, and bring them to justice."

French police are also continuing to investigate the circumstances surrounding the incident, alongside their British counterparts, the NCA said.

It added 55 people who were believed to have been on board the boat which arrived in Britain had also been identified.

More than 6 000 people have arrived in Britain this year via small, overloaded boats - usually flimsy inflatable dinghies - that risk being lashed by the waves as they try to reach British shores.

The deadly crossing on Tuesday took place just hours after the British parliament passed a bill paving the way for asylum seekers who arrive in Britain without permission to be deported to Rwanda, a policy which Prime Minister Rishi Sunak argues will deter people from making the dangerous cross-Channel journey.