Two children and two adults have died in a migrant boat tragedy yesterday, according to French authorities.

The five-year-old, eight-year-old and two adults were among the people involved in the tragedy off the coast of northern France, with more than a dozen taken to hospital for treatment.

Searches continue to be carried out for any other people who may still be at sea. The alarm was raised by a yacht which notified search and rescue, prompting French patrol boats, a Belgian helicopter and a fishing boat dispatching.

The people on board are thought to have been trying to cross the Channel to reach the UK, despite high winds of up to 18mph.

READ MORE: Two children among four dead after migrant boat sinks off French coast

Now, charity bosses are warning that the tragedy should serve as a "wake-up call" for UK and French leaders. 

Clare Moseley, who founded the refugee crisis charity Care4Calais, has said a way must be found to put an end to "terrifying, dangerous sea crossings."

It is believed to be the single biggest loss of life during the current migrant crisis, and brings the total number of deaths since 2018 to 10.

Ms Moseley said: “We are grieving for the victims, we stand in sympathy and solidarity with their families and friends.

“It is cruel and horrifying that, this time, young children are among the victims.

She added: “We have to provide a safe and legal process by which refugees can have their UK asylum claims heard, that’s the way to put an end to terrifying, dangerous sea crossings and stop tragedy striking again.”

Charity Save the Children has also urged French and UK leaders to treat the news as a "wake-up call".

A spokesperson for the charity said: “Today’s tragic news must be a wake-up call for both London and Paris to come up with a joint plan that ensures the safety of vulnerable children and families.

“The English Channel must not become a graveyard for children.”

Prime Minister Boris Johnson said the UK had offered “every support” to French authorities as they investigate the “terrible incident”.

And Home Secretary Priti Patel said she was “truly saddened” to learn of the “tragic loss of life”.

Military resources and civilian boats were involved in the rescue operation after the vessel was seen in difficulty near Dunkirk.

Fifteen people were taken to hospitals in Calais and Dunkirk, according to the Maritime Prefecture of the Channel and the North Sea.

Searches were paused at 5pm due to lack of light and French authorities stress any assessment on numbers is provisional.

An investigation into the causes of the sinking has been launched by the Dunkirk public prosecutor.

French citizenship minister Marlene Schiappa said she learned of the tragic incident with “great sadness”.

She added: “Despite the resources of the state, which were all mobilised in the SOS operation, the losses are heavy and the final toll is still uncertain.”

In a statement released yesterday evening, Ms Patel said she was “truly saddened” to learn of the deaths and reaffirmed her commitment to targeting people smugglers.

She said: “We are in touch with our French counterparts who are leading on the response and have offered whatever support they need as they investigate this incident.

“This tragic news highlights the dangers that come with crossing the Channel and I will do everything I can to stop callous criminals exploiting vulnerable people.”

Prime Minister Boris Johnson commented: “My thoughts are with the loved ones of those who tragically lost their lives in the Channel today.

“We have offered the French authorities every support as they investigate this terrible incident and will do all we can to crack down on the ruthless criminal gangs who prey on vulnerable people by facilitating these dangerous journeys.”