At least 92 people drowned and around 200 were believed missing after a boat carrying up to 500 African asylum seekers caught fire and sank off the Italian coast on Thursday, officials said.

“We have 92 dead and 151 people saved. We are looking for more survivors in the water,” a coast guard spokesman told AFP, adding that the search had been going on for more than 6 hours.

“We received the first alert at 7:00 am (0500 GMT) when a boat reported people in the water,” he said.

Giusi Nicolini, the mayor of Lampedusa island near where the incident happened, told news channel SkyTG24: “The survivors are in a state of shock”.

“They have been in the water since the early hours of the morning,” Nicolini said.

A local doctor said a 3-year-old boy and a 2-year-old girl were among the victims.

The accident was the latest in many drownings involving migrants travelling on rickety fishing boats or rubber dinghies in the Mediterranean, where thousands have died in recent years.

“The first assistance was provided by people on pleasure boats who heard the screams,” Antonino Candela, a local emergency medical worker, said.

Nicolini said the migrants had told her they lit a small fire on their boat around half a mile from the shore to attract the attention of coast guards after their vessel suffered engine failure.

The fire then spread, sowing panic on board which caused the boat to flip over and eventually sink.

Shaken survivors wrapped in thermal blankets — many of them bare-chested — were seen arriving on the dock in images shown on Italian television, as an emergency worker broke down in tears.

The bodies were being taken to a hangar at the local airport because there was no more room in the local morgue on the remote southern Italian island, which has a population of around 6,000.

“This is a tragedy without precedent. In many years of work here I have never seen anything like this,” Pietro Bartolo, a local doctor, was quoted by the Italian news agency ANSA as saying.

“We don’t need ambulances unfortunately, we need hearses,” Bartolo said.

“There are still hundreds missing,” he added.

As hopes faded of finding more survivors, the coast guard, border patrol, fire brigade and navy were all taking part in the search and were joined by fishing trawlers and pleasure boats.

The asylum-seekers said they were from Eritrea and Somalia and local police were quoted as saying they believed the boat had left from Libyan shores.

“We left 2 days ago from the Libyan port of Misrata. We were 500 on that boat, we could hardly move,” one survivor said, ANSA reported.

“3 fishing boats spotted us during the crossing but did not rescue us,” he said.

Prosecutors have opened an inquiry for multiple murders, as well as favouring illegal immigration.

A young Tunisian man believed to be 1 of the crew members has been detained, ANSA reported.

Italian prime minister Enrico Letta called the incident “an immense tragedy” in a tweet.

Pope Francis, who visited Lampedusa in July to plead for more tolerance and attention to the plight of refugees, called for prayers.

“This is shameful,” the pope said at a Vatican conference. “Let us join forces so these tragedies never happen again.”

The local archbishop, Francesco Montenegro, said: “We cannot keep on counting the dead. We have to mobilise, do something concrete to avoid these constant tragedies of despair”.

Lampedusa is an Italian island lying between Tunisia and Sicily and is a major entryway for asylum-seekers into the European Union, with thousands arriving every year.

“I am dismayed at the rising global phenomenon of migrants and people fleeing conflict or persecution and perishing at sea,” UN High commissioner for Refugees Antonio Guterres said in a statement.

There has been an increase in the incidents off Italy in recent weeks amid an upsurge in arrivals — mainly from Egypt, Eritrea, Somalia and Syria.

On Monday, 13 Eritrean asylum-seekers drowned as they tried to swim ashore when their boat ran aground off Sicily near the city of Ragusa.

In a similar incident near Catania in another part of Sicily in August, 6 young Egyptian men drowned trying to reach the shore.