Protesters clashed with police guarding a border fence in northern Greece Saturday, following a series of sea accidents that killed dozens of migrants and a warning from authorities that the death toll is likely rise in coming weeks.

About 500 anti-government protesters, who traveled from Athens and several towns in northern Greece were involved in the clashes near the border with Turkey after challenging a police cordon blocking access to the fence that spans more than 10 kilometers (6.2 miles).

The demonstrators are demanding that Greece tear down the fence and allow refugees to cross by land instead of risking their lives on the sea crossing to Europe. The youths, many wearing hoods and balaclavas, hurled rocks at police who responded with tear gas and stun grenades.

No arrests or injuries were reported.

The government says it cannot remove the fence for "practical reasons" and has called on other European Union countries to speed up additional support promised for search and rescue operations in the east Aegean Sea.

Greece is struggling to cope with a surge in arrivals, many fleeing the civil war in Syria and other conflicts, and the crossing is becoming increasing deadly as winter approaches.

More than 60 people, half of them children, have died in the past four days while trying to reach Lesbos and other Greek islands from the Turkish coast.

Most of the recent deaths have occurred in an 8-kilometer (5-mile) stretch of sea separating Turkey from the northern coast of Lesbos.

The head of the island's port authority, Coast Guard Lt. Cdr. Antonios Sofiadelis warned that smugglers were using increasingly dangerous tactics.

"Many of the boats are going for scrap and they use them for one last trip," he told The Associated Press in an interview. "Smugglers usually take the boats to the edge of Greek waters and then get picked up by speed boats. The people on the boats usually have no experience at sea."

Sofiadelis warned that more fatal accidents are likely as the weather worsens and smugglers become increasingly brazen.

"We have 50 to 60 crossings a day to Lesbos and sometimes half of those boats are in distress. We typically have five or six (serious) rescue operations every day. We simply can't be everywhere at the same time. So unless something changes on the Turkish coast, there will be more deaths."

Despite rough seas, thousands more people arrived on Lesbos on Saturday, mostly by dinghy. Many camped on a hill next to a police registration center where refugees obtain travel documents.

Afghan Nagib Akhbari warmed himself by a fire in a large basin of scrap metal as his son assembled a tent.

"I came with my five children and wife. We (crossed) Afghanistan, Iran, Turkey in eight days," said Akhbari, who looked exhausted and had bloodshot eyes.

"They took my money," he said, referring to payments to smugglers and an incident in eastern Turkey when he said he was robbed. "I have nothing now."

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Kantouris reported from Thessaloniki, Greece

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