The health ministry also said on its Twitter account that the number of documented deaths had risen by 15 to 1,709 so far.
Poland was considered one of the countries that had managed the pandemic relatively well, with a total of 45,031 infections so far. It began relaxing restrictions, including a ban on leaving home without a purpose, in May.
In July, before a presidential election that was won by an ally of the ruling Law and Justice (PiS) party, Prime Minister Mateusz Morawiecki told voters that COVID-19 is a disease "like any other."
But in recent days the number of new infections has climbed higher. The health ministry blamed outbreaks in coal mines and said it expects the numbers to fall to around 300 a day next week after the planned isolation of sick people.
Quarantine may be reinstated for people returning from some countries, government spokesman Piotr Muller said on Thursday, citing Spain and France as countries triggering concerns about the coronavirus.
"We are considering introducing a quarantine for particular countries from the European Union and from outside of the European Union," Muller told private broadcaster Polsat News.New infections were detected mainly in two regions, including the coal mining region of Silesia, said health ministry spokesman Wojciech Andrusiewicz. He also told private broadcaster TVN24 that a "high number of new infections" may occur in the coming days.