Thousands of children in northern Germany became the first in Europe to begin a new school year on Monday, with the rest of the country watching anxiously as full-time classes began after months of curtailed hours over the coronavirus pandemic.

Masks will be a daily accessory for some of the 150,000 children returning to school in the Mecklenburg-Western Pomerania region, Germany's first state to reopen the school gates after the summer holidays.

Education ministers of Germany's 16 states had agreed that schools will reopen full-time after the summer break, after offering only partial hours in the weeks when the lockdown was eased.

With infection numbers once again creeping up, fears are rising that the new school start could yet prove temporary.

But officials warn that children cannot afford to miss more school.

"The children need to be present in school because we have to prevent more lost time," Steffen Kaestner, headteacher of the CJD Jugenddorf-Christophorus school in Rostock, told Agence France-Presse (AFP).

Strict rules have been drawn up to limit transmission of the new coronavirus, with cases across Germany rising above 500 per day in recent weeks.

Different age groups are being taught separately so that if a pupil tests positive, only one class will have to go into quarantine and the rest of the school can remain open.

Masks must be worn in the corridors, classrooms regularly ventilated and pupils are required to wash their hands regularly and avoid hugging.

CJD has 1,350 students aged 9-18. Only two are missing, a decision by their parents, "who belong to a risk group," said the headteacher, but all the teachers are present.

Mecklenburg-Western Pomerania has so far been the German state least hit by the coronavirus, with only 20 deaths out of a total 9,148 in Germany since the beginning of the crisis.