Riot police were dispatched to the Greek islands of Lesbos and Chios on Monday as the government prepared to launch the construction of new controversial migrant camps.
In both islands, police deployed at the harbour to facilitate the landing of security force reinforcements from the mainland, state agency ANA said.
There are over 38,000 migrants crowded into camps on the Greek islands of Lesbos, Samos, Chios, Leros and Kos despite an official capacity of 6,200.
Prime Minister Kyriakos Mitsotakis over the weekend insisted that the plan would go ahead despite local opposition.
"The works will begin immediately and will be completed. There is no turning back," he told conservative party cadres on Sunday.
Work on the new camps on Lesbos and Chios, with a capacity of up to 7,000 each, is to begin this week.
More From This Section
Island officials and residents have told the Greek government that after five years on the front lines of the European migration crisis, they are no longer prepared to accept thousands of asylum-seekers.
Residents have threatened to block access to the new camp sites in order to hobble their construction.
The conservative government which came to power in July has announced that the camps on Lesbos, Samos and Chios will be shut down this year, to be replaced with new, smaller facilities that are to be operational by mid-2020.
But while the adminstration of Mitsotakis tries to alleviate the problem by relocating thousands of migrants to other parts of Greece, many communities on the mainland have also stonewalled the move.
The UN's refugee chief on Friday called for urgent action to address the "shocking and shameful" conditions migrants are forced to live in at reception centres on the Greek islands.
The United Nations High Commissioner for Refugees (UNHCR) Filippo Grandi said swift measures were needed to reduce overcrowding and improve living conditions on the islands prioritising water, sanitation and healthcare, as the winter weather was exacerbating the situation.