The coronavirus pandemic in Germany is "under control" thanks to measures imposed after an early surge in cases, Health Minister Jens Spahn said on Friday.

Imposing restrictions to keep people home from mid-March had been successful, Spahn told reporters in Berlin, as the country prepares to ease the measures and ramp up production of protective masks.

"The infection numbers have sunk significantly, especially the relative day-by-day increase. The outbreak is today again under control."

On Wednesday, Chancellor Angela Merkel announced that smaller shops would open from next week and schools reopen to some pupils from May 4.

But other elements of the wide-ranging restrictions will remain in effect, including a ban on gatherings of more than two people in public and on large public events.

On Thursday, the Robert Koch Institute (RKI) for disease control released data showing each disease carrier in Germany was infecting fewer than one other person -- the person-to-person rate dropping to 0.7.

The figures justified a first easing of the lockdown with a review after two or three weeks, Merkel said, while warning that there was "little margin for error" and that "caution should be the watchword, not over-confidence".

As Germany prepares to allow public life to resume, Spahn said the country would produce up to 50 million masks a week from August.

Some 40 million would be surgical masks and 10 million would be FFP2 masks, which offer more protection.

But so far Germany has not aped neighbouring Austria by introducing a nationwide requirement for people to wear masks in public, issuing only a "strong recommendation".

Defending the decision to hold off a mask requirement, Spahn said people had been "very responsible" so far.