Chancellor Angela Merkel warned on Tuesday there could be no further relaxation of coronavirus restrictions while Germany grapples with a surge in new infections.

She urged Germans to follow the rules on hygiene precautions and reminded travellers returning from risk areas that quarantine was not an option "but a must" so long as they could not show a negative test.

"We are seeing that an increase in mobility and closer contacts are leading to a higher number of cases," Merkel told a press conference in Duesseldorf.

"I believe there can be no further loosening (of restrictions) at this point," she said in her first public comments on the pandemic since returning from her summer break.

Germany was seen as an early success story in suppressing the virus but its progress has been undermined in recent weeks as numbers have crept up over the summer holidays.

Much of the rise has been blamed on returning holidaymakers as well as parties and family gatherings.

Germany has in recent weeks reported an average of well over 1,000 new cases a day, compared with around 350 in early June.

"This is a trend that cannot continue and must be halted," Merkel told reporters.

"When I say we need to pull in the reins I mean the rules need to be enforced very consistently."

Germany earlier this month introduced free, mandatory tests for people returning from areas deemed a high risk for COVID-19 infections.

People awaiting their results must stay in quarantine at home until the test comes back negative, Merkel said, warning that those who fail to comply faced fines.

She also welcomed tougher checks on compliance with hygiene precautions on buses and trains, such as mask-wearing and keeping a physical distance from others.

"If we comply with all of this the good news is that much of public life can carry on, everyone can do their bit," Merkel said.

As of Tuesday, Germany has recorded a total of 225,404 coronavirus cases and 9,236 fatalities.