Thousands of Albanians formed an enormous queue of cars at the Greek border Friday as they rushed to re-enter the country for work ahead of new virus rules, police said. 

Around 4,000 cars were jammed in a 20-kilometre-long (12-mile-long) line at the Kakavia border crossing in southern Albania, in a build up that has been growing since Greece announced tougher entry requirements at the start of the week to contain a surge in infections.

The changes came as thousands of Albanians who live and work in Greece, mainly in the agriculture sector, were preparing to return after summer holidays at home.

Under Athens' new rules, daily arrivals from Albania will be capped at 750 after August 16.

Albanians will also have to have to present a negative COVID-19 test carried out within 72 hours of their arrival and self-isolate for seven days.

Currently, those entering from Albania take virus tests at the border and provide contact information in case they are positive.

Some cars have been waiting for three days already, according to an Albanian police source, who told AFP that "Greek health teams are working with a reduced number of staff" and that the border post is closed at night.

Albania's Ministry of Foreign Affairs said in a statement that Greek authorities were trying to ease the logjam by increasing the number of tests from 200 to 300 per hour.

Police broadcast images of officers distributing water bottles to families struggling in the heat, while Albanian President Ilir Meta said he was "worried" about the situation. 

Infections have been on a steady rise in Albania, where some 220 people have died from COVID-19, according to the official toll.

Doctors warn the situation is deteriorating while the authorities have blamed citizens for failing to respect safety instructions.