Protesters have let off an explosive outside a police station in Kos, in the latest of a series attacks on officers which have included firebombs, flares and firecrackers.

Dozens of protesters also clashes with police on the island this weekend during a rally opposing a controversial migrant and refugee screening centre, construction of which is already underway.

Four teams of riot police were sent to the eastern Aegean island on Friday to guard the disused army camp at Pyli, which is being converted into the screening centre.

Fury: Riot police clash with locals in Pyli, outside the military camp where Greek authorities are building a controversial migrant and refugee screening centre

Aggression: Tyres burn outside the military camp, which is being guarded by four teams of riot police after violent protests over the construction of the centre broke out

On Sunday, six youths aged between 17 and 24 were arrested for launching attacks on riot squads, before the explosive went off on Monday afternoon.

Attacks on police officers have become so common that the officers’ union expressed fears that the situation on the island may go the way of Keratea – a Greek town where months-long protests and attacks on officers prevented the construction of a landfill site.

Protests were also reported close to the northern city of Thesaloniki on Sunday, and rival protests in Pireaus, close to Athens, on Monday.

It has been decided that a referendum will be held as to whether to continue the construction of the centre.

Kos Mayor Giorgos Kyritsis said: ‘Since government officials and the local MP believe that the citizens of Kos are in favour of [the centre], I have instructed the municipality’s general director to explore the procedures for an immediate local referendum so that citizens can decide whether they are in favour or opposed to [the centre] that is being constructed.’

Pressure is being piled on Greece by EU partners to open five such screening centres by next week, or risk being excluded from the passport-free travel of the Schengen zone.

Clashes: Pressure is mounting on Greece to open five screening centres by next week's deadline, with EU partners threatening to exclude it from the Schengen zone if it can't exercise control over the incoming wave of asylum-seekers landing on its shores

Pressure: Greece announced this week that it will meet the deadline for the centres. The country was the main gateway to Europe for more than a million refugees and migrants who reached the EU last year

Greece announced this week that it would have the migrant and refugee screening centres up and running by next week.

Defence Minister Panos Kammenos said Greece would meet a mid-month deadline to complete the five centres – also known as ‘hot spots’ – on the islands, as well as two relocation centres on the mainland.

‘The Defence Ministry has undertaken a pledge to complete the work for the centres by February 15,’ Mr Kammenos told reporters.

But Greek authorities are struggling to cope with the increasing flow of asylum-seekers arriving on its islands, while still navigating an exit from one of the worst debt crises in decades.

Greece was the main gateway to Europe for more than a million refugees and migrants who reached the EU last year.