Authorities in North Macedonia have filed criminal charges against three Pakistanis and a Macedonian man for allegedly imprisoning a group of migrants and holding them to ransom, officials said on Monday.

The prosecutor’s office said the men were believed to have behaved in a “particularly degrading and cruel” manner to the 12 migrants, including two minors, from India, Afghanistan and Pakistan.

They were allegedly detained for two weeks in October in a house in the country’s north. The four suspects were arrested last year but the arrests were announced on Monday.

According to the prosecution, the suspects “caused [the migrants] to lose their sense of time, gave them food only once a day and physically abused them”. They also allegedly demanded money from their prisoners’ relatives in other European countries and threatened to kill the migrants when they asked to be freed.

One migrant managed to contact relatives who reported the case to Serbian authorities, who in turn informed police in North Macedonia, the prosecutor’s office said.

The three Pakistanis were arrested and are in custody pending trial. If convicted, they face up to eight years in prison. The Macedonian national, who owns the house where the migrants were allegedly being held, has also been charged and is under house arrest.

North Macedonia is a key stage on the route many migrants take through the Balkans towards prosperous European countries after illegally entering neighbouring Greece — mostly on small smuggling boats from Turkey.

On the Greek island of Lesbos, where most of the boats arrive, migrants clashed with police on Monday during a protest over severe overcrowding at the local Moria camp and delays in Greece’s asylum procedure.

Riot police used tear gas to disperse several hundred protesters who had planned to march from the camp to the island capital of Mytilene, about 5 kilometres (3.1 miles) away. No arrests or injuries were reported.

Also on Monday, police in Cyprus said they safely escorted to the coastal town of Larnaca a boat with 87 Syrian migrants that had left from the Turkish port of Mersin and was spotted by radar off the island nation’s southeastern tip.

The 61 men, 10 women and 16 children were taken to a reception centre outside the capital Nicosia.