Greek riot police fired tear gas on Sunday at demonstrators protesting against the development of a centre to house migrants on the tourist island of Kos, officials said.
About 2,000 people joined a rally against the so-called "hotspot" centre being built on the Aegean island despite the opposition of local residents and the mayor, fearful of the effect on the vital tourism industry.
Riot police fired tear gas to disperse several dozen protesters who tried to break in to the construction site about 10 kilometres (six miles) from the port of Kos, the island's deputy mayor David Gerasklis told AFP, confirming media reports.
The protest followed a rally last Wednesday in the port which drew about 1,000 people.
"The number of demonstrators Sunday was bigger than on Wednesday, about 2,000 people," said Gerasklis.
Greece has pledged to build five "hotspots" to house and process migrants on the islands of Kos as well as Chios, Leros, Lesbos and Samos.
Situated just a few kilometres from the Turkish coast, the scenic tourist idylls have become the gateway to Europe for tens of thousands of people fleeing war and poverty in hope of a better life.
EU member states last week gave Brussels a three-month deadline to remedy "deficiencies" in controlling the influx of migrants, or effectively face suspension from the 28-nation bloc's passport-free Schengen zone.
Dutch Foreign Minister Bert Koenders, whose country currently holds the EU's rotating presidency, held talks with Greek premier Alexis Tsipras in Athens and agreed on the need to work "efficiently" to clamp down on migrant traffickers.
Koenders said he wants to work to improve cooperation and coordination between EU countries to ease the migrant crisis gripping the continent.