Demonstrators on the Greek islands of Lesbos and Chios protested against government plans to build migrant detention centres for a fourth consecutive day on Thursday.
The protests come amid growing anger and occasional violence on islands that are the main entry point to the EU for tens of thousands of people seeking better lives.
Shops and services were shut on Lesbos as workers extended an initial 24-hour strike into a second day as part of the protests.
The mayors of Lesbos, Chios and the nearby island of Samos met with Prime Minister Kyriakos Mitsotakis on Thursday evening.
They agreed on “the need to immediately ease overcrowding on the islands", Mr Mitsotakis's office said after the meeting.
It announced that in coming days he would visit all three islands, starting with Samos, whose migrant camp has the most severe overcrowding.
On Wednesday, protests sank into violence with hundreds of demonstrators armed with petrol bombs, shotguns and stones attacking police at building sites on Chios and Lesbos.
A crowd also laid siege to a Lesbos army camp where riot squads were staying.
Officials said 43 police officers were injured in the violence on Lesbos, and another nine on Chios, where a mob burst into a hotel being used by police and beat officers resting in their rooms.
The government has said it will pull out many of the riot police sent to the islands this week.
But it insisted its plan to tackle migration would go ahead. The plans include building the new centres, speeding up asylum procedures and deportations, and increasing border controls.
“It is the only plan that can be implemented,” Mr Mitsotakis said in opening remarks at a Cabinet meeting on Thursday morning.
He condemned the attacks against police officers, saying those who took part in the violence “will be located and will answer for their actions”.
“At the same time, however, incidents of excessive violence by the police will be investigated,” Mr Mitsotakis said.
“Serious accusations have been made. We have a duty to investigate them.”
Mr Mitsotakis said he ordered a “significant increase” in the number of patrol boats and patrols after an increased public health risk from the new coronavirus, because new arrivals include people from Iran and Afghanistan.
Greece’s eastern Aegean Sea islands have been the main entry point into the EU for tens of thousands of people fleeing conflict and poverty in the Middle East, Africa and Asia.
Under a 2016 deal between the EU and Turkey, new arrivals must stay on the islands pending deportation back to Turkey, until their asylum applications are processed.
Island residents have demanded that all migrants be moved to the mainland, and vehemently object to new camps being built in their areas.