Greece has sent troops and police reinforcements to Lesbos after renewed clashes between police and migrants, the public broadcaster says, while Syrian refugees on the island have been targeted with Molotov cocktail attacks.
Authorities are working to "relieve the island as quickly as possible of a large number of refugees, so that the flow can be brought back to a tolerable level," deputy migration minister Ioannis Mouzalas said on Sunday as he visited the island.
Lesbos is one of several Greek islands struggling to cope with a huge influx of people arriving in flimsy boats from Turkey, most of them refugees fleeing war-torn Syria.
More than 230,000 people have landed on Greek shores this year and the numbers have soared in recent weeks as people seek to take advantage of the calm summer weather.
There have been repeated clashes on Lesbos between police and migrants - and between migrants themselves - over delays in the registration process that have left thousands of refugees stuck on the island, unable to continue their journey to other countries in Europe.
A police source said a pair of attackers on a motorbike threw two Molotov cocktails at refugees sleeping in parks in the island's main town, Mytilene.
A Syrian was lightly injured in one of the attacks, the source said. State news agency ANA said two 17-year-olds were arrested over the assaults on Friday morning.
Riot-police used batons Sunday morning to beat back a crowd waiting to be registered, after scuffles broke out between Syrians - who are granted priority in the process - and Afghans forced to wait for much longer, public TV channel ERT 1 said.
Two extra riot squads arrived on the island on Sunday while 60 more ordinary police officers have been dispatched to speed up the registration process, ERT 1 said.
The army has also been mobilised to distribute food and set up refugee camps.