Six players from Red Star Belgrade have tested positive for the coronavirus, the reigning Serbian champions announced on Saturday, as the country suffers an upsurge in the pandemic.

"These players will not take part in the first phase of pre-season training and will be in isolation for the next two weeks," the club said in a statement.

"Red Star are taking all necessary protective measures," the statement added.

The club had already announced that five players were positive on June 22, two days after its players celebrated their title in front of 18,000 spectators.

After containing a first wave of the epidemic with strict measures, the Serbian authorities opted for a rapid easing of lockdown restrictions, including mass sports events. On Friday, with 18 deaths, the country of seven million people experienced its deadliest day since the start of the pandemic.

Football is not the only sport in Serbia affected by Covid-19.

On June 22, the Serbian Basketball Federation cancelled a national team training camp scheduled from June 25 to July 5 because two players had tested positive.

The following day, world tennis No.1 Novak Djokovic announced that he tested positive for coronavirus, probably contracted on the sidelines of a charity tournament he was organising in the Balkans. He resumed training last Tuesday.

Three other players who took part in the Adria Tour, which started in mid-June in Belgrade, Bulgarian Grigor Dimitrov, Croatian Borna Coric and Serbian Viktor Troicki, also tested positive.

Croatian Goran Ivanisevic, director of one of the stages of the Adria Tour and one of Djokovic's coaches, also announced that he had tested positive.

The pandemic has officially killed 370 people in Serbia. But in the last week there have been violent demonstrations, with protesters blaming the Serbian government for inconsistent handling of the pandemic and accusing it of deliberately minimising its scale.

In a further sign of the pandemic's resurgence in the region, Albanian club Partizani, announced that five of their players had tested positive and been withdrawn from the their derby with league leaders KF Tirana on Friday. The match ended 1-1.

"The players are feeling well and are in strict quarantine, in constant contact with the medical team," a club spokesman told AFP.

Since the start of the pandemic, 3,371 people have tested positive for the coronavirus in Albania, 89 of whom have died. With 90 new cases on Friday, Albania suffered its biggest daily increase.