A six-year-old boy washed up on a Spanish beach and two young brothers trying to reach their father in France are among the child refugees dying in desperate journeys across the Mediterranean as Europe continues to turn its back on their plight.

In tragic scenes echoing the death of the three-year-old Alan Kurdi in 2015, which ignited global calls for asylum seekers to be granted safety, a boy’s body was found by authorities on the shoreline in Cadiz.

Its state of decomposition led Spanish authorities to believe he was among a group of at least six migrants from sub-Saharan Africa who drowned a fortnight ago while trying to cross the Strait of Gibraltar.

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The body of the boy, estimated to be six years old, was found by a passing villager and officials are attempting to identify him to contact bereaved relatives.

Two more children died over the weekend as they attempted to cross the treacherous Central Mediterranean between Libya and Italy with their siblings.

The International Organisation for Migration (IOM) said the two brothers, aged five and eight, died of either hypothermia or suffocation in a packed dinghy launched from the Libyan port of Zuwara over the weekend.

They were with their two sisters, aged 10 and 14, and all were travelling from the Ivory Coast in an attempt to reach their father in France.

A French naval ship took around 150 survivors from West African countries including Nigeria, Burkina Faso and Guinea to shore in Trapani, Italy, and transferred them to a shelter.

“Crossing the Mediterranean is always dangerous for migrants, but at this time of year the sea conditions and the cold weather can be lethal, particularly for small children,” said Federico Soda, director of the IOM coordination office for the Mediterranean.

“It is unacceptable that children like these are dying while trying to reach Europe by sea. This year, crossings of the Mediterranean have continued throughout the winter because of the increasingly dangerous and unbearable conditions that migrants face in Libya every day.”

In pictures: A day of refugee rescues in the Mediterranean Sea Show all 7 1 /7 In pictures: A day of refugee rescues in the Mediterranean Sea In pictures: A day of refugee rescues in the Mediterranean Sea A baby being taken on to MSF's Bourbon Argos ship from a boat carrying 130 migrants and refugees Lizzie Dearden In pictures: A day of refugee rescues in the Mediterranean Sea A refugee boat carrying 101 people being rescued by MSF's Bourbon Argos Lizzie Dearden In pictures: A day of refugee rescues in the Mediterranean Sea A refugee boat carrying 101 people being rescued by MSF's Bourbon Argos all images by Lizzie Dearden In pictures: A day of refugee rescues in the Mediterranean Sea A baby among refugees on a boat carrying 185 people off the coast of Libya Lizzie Dearden In pictures: A day of refugee rescues in the Mediterranean Sea Migrants and refugees sleeping after being rescued by MSF's Bourbon Argos ship Lizzie Dearden In pictures: A day of refugee rescues in the Mediterranean Sea A crew from MSF's Bourbon Argos ship rescuing a boat carrying 130 migrants and refugees off the coast of Libya, at sunrise Lizzie Dearden In pictures: A day of refugee rescues in the Mediterranean Sea A woman in a stretcher being lifted onto MSF's Bourbon Argos ship from a boat carrying 130 migrants and refugees off the coast of Libya Lizzie Dearden

Another dead body was brought ashore in Sicily by the rescue ship Diciotti, with asylum seekers on board the dinghy saying two people fell overboard during the attempted crossing.

The remains of a Nigerian woman were also found among more than 204 migrants brought to the Italian island of Lampedusa on Sunday.

At least 254 refugees have died in crossings over the Mediterranean so far this year, following a record 5,000 deaths in 2016.

More asylum seekers have died on land in the continent they hoped would offer them safety, including victims of the freezing conditions gripping much of Europe this month.

A two-month old baby died at the Ritsona refugee camp in Greece on Friday, a day after being diagnosed with cystic fibrosis.

Doctors in Chalkida recommended a referral to a hospital in Athens but the parents returned to the camp, believing an ambulance would be sent after an apparent translation issue.

And three men have died in recent days on the Greek island of Lesbos, where the navy sent a ship to provide emergency accommodation after tents were buried in snow earlier this month.

A 20-year-old Pakistani man was found dead in his tent early on Tuesday morning in the Moria detention camp, and a 46-year-old Syrian man was found dead there on Saturday, following the death of a 22-year-old Egyptian man last week.

A migrant stands next to a snow-covered tent at the Moria detention camp on the Greek island of Lesbos on 7 January (AFP/Getty)

Charities have warned that thousands of refugees remain at risk in poor shelter and extreme weather conditions across Europe, where many have been stranded by travel restrictions and closing borders.

The dire situation comes after Donald Trump provoked international condemnation by freezing the US refugee programme and immigration from seven predominantly Muslim “countries of concern”.

“The needs of refugees and migrants worldwide have never been greater and the US resettlement program is one of the most important in the world,” the UN Refugee Agency (UNHCR) and IOM said in a joint statement.

The two agencies cautioned against proposals by the President to prioritise asylum claims by Christians – a move that could violate international law.

Boat crossings over the Aegean Sea have dramatically decreased since the EU-Turkey deal was struck in March, which has resulted in anyone arriving in the Greek islands detained under threat of deportation.

But voyages over the longer and more treacherous Central Mediterranean, now the deadliest crossing in the world, have continued throughout the winter, as well as journeys from North Africa to Spain to the west.

Almost 5,500 migrants have arrived by sea in Europe so far this year, according to UNHCR figures, in unseaworthy rubber dinghies and overloaded wooden fishing boats.