Residents of two Greek islands have clashed with riot police as authorities pushed ahead with plans to build new migrant camps.
Demonstrators on Lesbos and Chios tried to block equipment bound for construction sites on the islands.
Footage from Lesbos shows police firing tear gas while protesters donned surgical masks and blockaded roads.
Authorities plan to build a number of closed detention sites to house migrants on Greek islands.
Prime Minister Kyriakos Mitsotakis - newly elected in July - has pledged to build new camps to replace overcrowded facilities spread across Lesbos, Samos, Chios, Leros and Kos.
All five lie off the coast of Turkey, on a route where hundreds of thousands of migrants have tried to cross on the way to Europe in recent years.
But there has been intense local opposition.
What's happening on the islands?
Hooded demonstrators reportedly pelted riot police with rocks at the harbour on Chios as riot police sent from mainland Greece disembarked.
Protesters on Lesbos meanwhile blocked roads leading to a construction site with rubbish trucks and cars.
According to Greek reports, Regional Governor Kostas Moutzouris and West Lesbos Mayor Taxiarchis Verros both joined a road cordon with residents.
Dimitra Kalogeropoulou, Greek head of the International Rescue Committee, said the tensions should be no surprise, adding that overcrowding "is good for no one; local communities feel their islands have been transformed into giant prisons, while asylum seekers are forced to live in dangerous conditions".
Hundreds of thousands of migrants arrived on the Greek islands off Turkey en route from Syria to Europe in 2015 and 2016. Numbers have dropped since then after an EU deal with Turkey.
However, arrivals have been rising again and a total of 42,568 migrants are currently on the islands.
Some 19,000 people are currently housed at the Moria refugee camp on Lesbos - originally designed to accommodate fewer than 3,000.
There are similar levels of overcrowding at other sites spread across the islands.
Filippo Grandi, UN High Commissioner for Refugees, recently called for an end to the "shocking and shameful" conditions at the Greek camps.
Mr Mitsotakis and his conservative government have taken a tougher line on migration. The Greek government recently invited proposals for a floating barrier to block migrants from arriving by sea.