Athens - More than 100 illegal migrants were detained on two Greek islands over the weekend, the coast guard confirmed Sunday.

On Lesbos, 60 migrants were picked up Saturday, bringing to 11,000 the number detained on the island so far this year. On the Dodecanese islands to the south, 42 were taken into custody.

Officials said the smaller Dodecanese islands were overwhelmed with migrants. On Agathonissi, which has a population of 80, some 4,300 refugees have arrived since the beginning of the year.

"We cannot really help them," the island's mayor, Evangelos Kottoros, said on Sunday. "They spend three or four days in the open before they are collected."

The United Nations High Commissioner for Refugees warned last week that reception centres for migrants on islands in the Aegean Sea were badly overcrowded.

On Samos, 600 migrants are currently housed in a centre built to accommodate 280, according to the international relief group Medecins Sans Frontieres, also known in English as Doctors Without Borders.

The Aegean is one of the main European transit routes for human traffickers. Greece is home to an estimated 1 million non-EU citizens, about a third of whom are in the country illegally. dpa