Niki Kitsantonis

At least 78 people drowned in the Aegean Sea after a large fishing boat carrying migrants sank early Wednesday, the Greek Ministry of Shipping said, in the deadliest episode off the country's coast since the height of the 2015 migration crisis.

More than 100 people were rescued, but the Greek Coast Guard warned that the death toll could rise.

The ship ran aground about ‌50 miles southwest of the town of Pylos, in southern Greece, on Wednesday after authorities were notified of its unusual movement the day before. according to a statement of the Greek Coast Guard.

The coast guard said the ship had refused help offered by the authorities, but cargo ships in the area had been providing food and water to migrants who were rescued after the boat sank.

A Greek Shipping Ministry official said the ship had departed from Tobruk, Libya, and was traveling to Italy.

The cause of the sinking as of Wednesday afternoon was not clear.

Greek authorities said the coast guard and military had deployed a large number of boats in “widespread search and rescue operations” to reach survivors and find the dead, many of whom they said were migrants from Egypt, Pakistan and Syria.

It's not clear how many people are still missing, but interviews with survivors will hopefully shed some light on the scale of the tragedy.

President Katerina Sakellaropoulou is on her way to the port of Kalamata, in southwest Greece, her office said. Local authorities there have set up an open-air clinic to provide first aid to survivors.

The sinking was the deadliest episode off the coast of Greece since 70 people died when a boat carrying migrants sank near the offshore island of Lesbos in October 2015, according to the International Organization for Migration.

Last year, nearly 3,800 migrants died on routes in and from the Middle East and North Africa region, according to a new annual report by the organization – the highest death toll in five years, the report says. Given the dearth of official data, the actual number of deaths in the migration route may be much higher, he said.

“As many as 84 percent of those who died along the sea route remain unidentified, leaving families desperate for answers,” the report said.

Some of the worst disasters with migrants at sea occurred in 2015 and 2016 when hundreds of thousands of people tried to reach Europe. In one sinking, in April 2015, an estimated 800 people died near Libya; a year later, the United Nations says that as many as 500 people died when a boat full of migrants capsized en route to Italy.

The fatal drowning occurred during the election campaign in Greece where the country's policies on migrants have become a central issue. The current prime minister, Kyriakos Mitsotakis, defended his government's stricter migration policies, arguing that the previous government's more lenient stance had put undue pressure on the country and increased deaths at sea.

Mr Mitsotakis imposed a crackdown on migration during his time in power, increasing border controls in a bid that led to a 90 percent drop in migrant arrivals since 2015. Rights groups accuse his government of illegally pushing back migrants at sea and building camps in prison-like conditions, and the video verifies by The New York Times shows the Greek Coast Guard in April rounding up asylum seekers, among them young children, and leaving them on rafts out at sea.

However, many people in Greece, particularly in the border areas, welcome the reduced number of arriving migrants.

Greece's Migration Ministry said on Wednesday that the drowning victims also demonstrated the urgent need to tackle the smuggling of migrants across international borders.

“This sinking has once again brought to the fore, in the most tragic way, the need to break down international smuggling networks that endanger the lives of migrants,” the ministry said in a statement.