Health Minister Kiril Ananiev on Monday ordered Bulgarians to resume wearing masks again at all indoor public venues after the Balkan country last week recorded its highest weekly rise in novel coronavirus cases.

"All persons who were without protective face masks in the church at the Rila Monastery during the prime minister's visit will be fined," the health ministry told Reuters in an email.

As well as Borissov, journalists, photographers and camera people who accompanied him into the church without masks will also be fined, the ministry said.

It did not say whether clergy who failed to wear masks inside the church would also be penalized.

The Eastern Orthodox Rila Monastery, which nestles in the Rila mountains south of Sofia and is more than 1,000 years old, is famed for its colorful frescos and is one of Bulgaria's top tourist attractions.

Bulgaria has weathered the COVID-19 pandemic relatively well due to rigorous lockdown restrictions including the compulsory wearing of face masks in public places.

It had begun to relax the measures this month, but last week it reported 606 new COVID-19, bringing the total to 3,984, with 207 deaths, prompting Ananiev's decision to reimpose the mask requirement at indoor public venues, including trains and buses.

On Monday Chief State Health Inspector Angel Kunchev said Borissov's ruling center-right GERB party and the opposition Socialist Party would each be fined 3,000 levs for failing to enforce social distancing at recent large-scale events they organized.