GREECE'S prime minister has lashed out at European "ineptness" in handling the migration crisis after at least 26 more people drowned in new shipwrecks.

The Merchant Marine Ministry said 19 people were killed and 138 were rescued near the eastern Aegean Sea island of Kalymnos, as boatloads of Middle Eastern refugees and economic migrants try to reach the Greek islands in rough seas.

It was one of the worst accidents in Greek waters since the mass migrant flows started after the war in Syria, and another three died and six were rescued in a separate incident off the island of Rhodes.

The death toll in the Aegean over the past three days has now reached nearly 50.

Meanwhile in Spain, rescuers found the bodies of four migrants and are searching for 35 missing from a boat that ran into trouble trying to reach Spain from Morocco.

Greek premier Alexis Tsipras voiced sorrow at the new deaths, and lashed out at Europe's "inability to defend its (humanitarian) values" by providing a safe alternative to the dangerous sea journeys in frail boats provided by smuggling gangs.

"I want to express ... my endless grief at the dozens of deaths and the human tragedy playing out in our seas," he told parliament. "The waves of the Aegean are not just washing up dead refugees, dead children, but (also) the very civilisation of Europe."

He laid responsibility for the tragedy with western countries, whose military interventions in the Middle East "were not to introduce democracy ... but to serve financial interests".

"And now, those who sowed winds are reaping whirlwinds, but these mainly afflict reception countries," he added.

"I feel ashamed of Europe's inability to effectively address this human drama, and of the level of debate ... where everyone tries to shift the blame on to someone else."

Four coastguard patrol vessels, a helicopter and three fishing boats helped rescue the survivors off Kalymnos, and nobody was listed as missing, the Merchant Marine Ministry said. The accident occurred when the wooden boat sailing from Turkey took on water and sank in moderately strong winds.

At least three more people died when another boat sunk off the nearby island of Rhodes. Three people are still missing, while six were saved.

Meanwhile, authorities raised to 16 the number of deaths from another migrant ship disaster off the island of Lesbos on Wednesday. They said 274 people have been rescued and one remains missing.

Meanwhile, four children drowned and two others are missing after two boats carrying migrants from Turkey to the Greeks islands capsized in the Aegean.