Greek authorities on Wednesday blamed human traffickers for a collision between a coastguard vessel and a migrant boat which official said left at least 15 people dead, including four women.

The collision happened on Tuesday off Chios, near the Turkish coast, which like other Greek islands has become an entry point for asylum seekers trying to reach Europe.

Migration minister Thanos Plevris described the deaths as a ‘tragic incident’ during a debate in parliament about toughening criminal penalties against people-smugglers.

‘The criminals are the traffickers... who tried to drop off the migrants at Chios,’ he added. Large numbers of migrants seek to cross the Mediterranean each year to get to Europe.

Last year, more than 1,700 people died or went missing on migration routes to Europe in the Mediterranean and the Atlantic Ocean off west Africa, according to the UN refugee agency.

Since 2014, about 33,000 migrants have died or gone missing in the Mediterranean, the International Organization for Migration said.

The Greek coastguard said in a statement that the ‘high speed’ migrant vessel, which had no navigation lights, failed to comply with visual and audible signals.

‘Instead, the pilot turned around, and the boat then collided with the starboard side of the Coastguard patrol boat,’ it added.

‘The force of the impact caused the boat to capsize and sink.’

Fourteen bodies were retrieved from the sea, including three women. Another woman died later from her injuries, the coastguard said.

The survivors were of Afghan nationality, said Christos Tsiachris, director of the hospital on Chios that is treating them, Ert television reported.

Among the 25 rescued who have been taken to hospital were 11 children, and two injured coastguards.

Rescuers in five boats and a helicopter scoured the sea early Wednesday for other survivors or victims. Authorities said they did not know how many people were on board the boat.

The European Commission said it was following events and was in contact with Greek authorities, who have launched an investigation into the circumstances of the incident.

‘Every life lost at sea is a tragedy,’ said spokesman Markus Lammert.

‘At the hand of smugglers too many people risk their lives and lose their lives, and this is exactly what we’re working on to prevent, and this is also why our work with partner countries is so important.’