Migrant crisis: Chios island camp in Greece attacked
Unidentified assailants have thrown petrol bombs, fireworks and stones at migrants' tents in Souda, on the Greek island of Chios, forcing about 150 people to flee.
It was the second night of violence in and around Souda camp. About 4,000 migrants and refugees are on Chios.
Several tents, including one housing 50 people, were damaged in the violence, the UN refugee agency (UNHCR) says.
On Wednesday four migrants were arrested after fireworks were thrown.
Greek police said the four were three Algerian teenagers and an Iranian man. The fireworks were allegedly stolen from a shop.
More than 16,000 asylum seekers are still living in camps on Greek islands.
A UNHCR spokesman in Greece, Roland Schoenbauer, said that on Friday someone on the wall above Souda camp had thrown a stone, hitting a Syrian refugee on the head and seriously injuring him. He is now in hospital.
On Thursday night, "Molotov cocktails were thrown from the wall, which destroyed several tents", Mr Schoenbauer told the BBC. "People are scared - it's hard to convince them to go back [to Souda camp]."
The government-run camp is overcrowded.
Far right involvement?
The situation is still tense at Souda and the UNHCR has not managed to replace all the damaged or ruined tents.
"Volunteers helped with small tents outside the site," Mr Schoenbauer said, urging the Greek police to step up patrols in the area.
"Not all the migrants will have a dry place to spend the night because of the current insecurity there."
About 60% of the Souda refugees and migrants are Syrians, 20% Iraqis, 10% North Africans and 10% other nationalities.
Two local aid workers were also assaulted by a crowd of about 30 people and needed hospital treatment in Thursday's violence.
According to some reports, Greek far-right militants were involved in the violence.
"Some 100 people lost a dry place to sleep in the first two incidents, so they'll get new tents," Mr Schoenbauer said. New blankets, sleeping bags and other items are also being provided.
The UNHCR has offered to help the Chios authorities to find new accommodation for migrants, whether in hotels, apartments or public buildings.
To ease the pressure, Mr Schoenbauer said, the UNHCR is also helping to identify asylum seekers for transfer to the Greek mainland, and arranging ferry tickets for them.
Some migrants have already been transferred, after being processed and receiving an asylum card.
According to the UNHCR, migrant arrivals on Chios are down to a daily average of six, compared with 21 in October. In April the daily average was 38.
Last month, violence also erupted at an overcrowded migrant camp on the neighbouring Greek island of Lesbos.
There has been a dramatic fall in the numbers of migrants making hazardous boat journeys across the Aegean from Turkey to the Greek islands since March, when the EU signed a deal with Turkey to curb the influx.
But the processing of asylum claims is very slow and tensions have risen between migrants and local residents. In many cases, migrants are sheltering in squalid conditions in Greece.
The Greek islands have been returning some irregular migrants to Turkey, after rejecting their asylum claims.
The UNHCR is not involved in those returns, Mr Schoenbauer said, but does not object, provided the correct safeguards are followed and the country of origin is safe.
A note on terminology: The BBC uses the term migrant to refer to all people on the move who have yet to complete the legal process of claiming asylum. This group includes people fleeing war-torn countries such as Syria, who are likely to be granted refugee status, as well as people who are seeking jobs and better lives, who governments are likely to rule are economic migrants.