Piontkowski said that, until then, schools would continue to hold classes remotely as the country continues efforts to curb the coronavirus epidemic.
He added he hoped regular classes would return in September, after the school summer holidays.
Poland on March 12 shut all schools and universities for two weeks as part of efforts to curb the spread of the coronavirus. The closure was then extended.
Polish elementary schools began reopening and offering daycare programmes to young children last Monday as the country lifted more COVID-19 safety measures.
A total of 23,987 people have tested positive for the COVID-19 disease in Poland, with 1,065 deaths from the coronavirus so far, public health officials announced on Monday morning.