KYTHIRA — Strong winds hampered efforts around two Greek islands Friday to find at least 10 migrants believed to be missing at sea after shipwrecks left at least 23 people dead, officials said.

A dinghy and a sailboat sank in two separate incidents late Wednesday and early Thursday off the islands of Lesbos, near the coast of Turkey, and Kythira, south of the Greek mainland — prompting a dramatic nighttime rescue, with survivors hauled to safety up cliffs.

Coast guard, navy and volunteer rescuers focused efforts around a rugged cove on Kythira where the sailboat smashed into rocks and broke up, leaving bodies floating in the wreckage on Thursday.

Greek Prime Minister Kyriakos Mitsotakis, who was in Prague for a meeting of European leaders, blamed Turkey for failing to stop boats crammed with migrants from leaving its coastline.

“Once again, I call on Turkey to cooperate with Greece to stop these ruthless networks of traffickers of people in distress so no more lives are needlessly lost in the Aegean Sea,” Mitsotakis told reporters at the start of the meet in the Czech capital.

“The root of this problem is the boats leaving the Turkish coastline,” he said. “And there is no doubt that Turkey, if it wants to, can do more to tackle this problem.”

Turkey maintains that Greece puts migrants’ lives at risk with reckless interceptions of boats at sea.

The International Organization for Migration, a United Nations agency, says that before the latest incidents off Lesbos and Kythira, it had recorded 237 people as dead or missing while attempting to cross the eastern Mediterranean route so far this year, out of a total of 1,522 migrant deaths in the Mediterranean.

“We have witnessed another two tragedies in the Mediterranean. People desperate for safety and better lives are risking everything in fatal journeys,” Gianluca Rocco, head of the IOM mission in Greece, said.

“This reiterates the need to intensify international cooperation to save lives and improve rights-based pathways for safe and regular migration.”

Several hundred people joined a demonstration in the main port of Lesbos, Mytilene, late Thursday, calling on authorities in Greece and Turkey to cooperate to save lives in the eastern Aegean Sea.

Wreaths of flowers were thrown into the sea to honor the victims who died off the Lesbos coast — 16 women, a boy and an adult man, most believed to be from Somalia.