Egyptian authorities have arrested four people in connection with the death of at least 43 refugees whose Europe-bound boat capsized off Egypt's Mediterranean coast.

Officials said on Thursday that the four were members of the vessel's crew, and would be remanded in police custody for four days pending further investigation.

They face charges of human trafficking and manslaughter.

Authorities also issued arrest warrants for five more people wanted in connection with Wednesday's shipwreck, according to officials.

"The death toll is going to rise," a medical source told AFP news agency. "On the boat there is a hold used to store fish. It hasn't been opened and there must be a lot of people inside."

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The Egyptian military said the boat was 12 nautical miles off the coastal town of Rosetta when it capsized.

Refugees drown after boat capsizes off Egypt's coast

Mohammed Sultan, the governor of Beheira province, where Rosetta is located, told the Associated Press news agency that authorities did not have a precise number for those who were on board the vessel, but between 250 and 400 seemed likely.

He said 157 people were rescued.

An initial breakdown of the nationalities of the people in the boat showed that they included 111 Egyptians, mostly teenagers and men in their 20s, according to Sultan.

There were also 25 Sudanese, while the rest were sub-Saharan Africans and Syrians.

The search for bodies and survivors has been expanded around the spot where the vessel capsized, said Sultan.

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Many of the survivors have been held by police, while those who suffered injuries were taken to hospitals, where they lie handcuffed to hospital beds under police guard.

Mohamed, a 28-year-old Egyptian welder, managed to stay afloat until a rescue boat found him, but lost his wife and son during the incident.

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He was arrested for trying to leave the country illegally.

"I risked my life and the lives of my son and wife so they could have a nice life," he told AFP from his hospital bed in Rosetta. 

Mohamed said the rising cost of living had prompted him to leave behind his homeland and head for Italy, where he would have looked for a "job doing anything".

He had agreed with a people-smuggler to pay an intermediary $5,600 when he reached Italy.

"I was the only one who survived. I wish I hadn't survived."

Experts say people smugglers in Egypt mostly use old fishing vessels, packed far beyond capacity both below and above deck.

Another survivor, Ahmed Darwish, blamed people smugglers for the tragedy, saying overcrowding caused the boat to capsize, and accused authorities of not reacting quickly enough.

"What happened was a wrong, it was wrong on our part first of all [to attempt the crossing], but it was also wrong on the part of the people [traffickers] who don't have a bit of mercy in their hearts," he told AP.

"The boat is meant to hold 200, and they put 400 in it. And this is what caused the catastrophe."

Darwish said he believed that many of those who died were women and children who could not swim.

"Those ... that knew how to swim moved away [from the boat], leaving behind women and small children," he said.

It is not yet confirmed by officials but the capsized boat was believed to be going to Italy.

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Thousands of people have made the dangerous sea voyage across the Mediterranean in recent years, fleeing war and poverty in the Middle East and elsewhere.

The number of people trying to cross the Mediterranean from Egypt to Europe has increased significantly in the past year, according to the EU border agency Frontex.

More than 12,000 people arrived in Italy from Egypt between January and September, compared with 7,000 in the same period last year, it said.

Some 206,400 refugees have crossed the Mediterranean this year, according to the International Organization for Migration.

More than 2,800 deaths have been recorded between January and June this year, against 1,838 during the period last year.

Source: News Agencies