Angela Merkel sat through ­national anthems on Thursday during an official ceremony, as the German chancellor sought to prevent a repeat of uncontrollable shaking with a rare change of protocol.

After greeting Denmark's new Prime Minister Mette Frederiksen at the portico of the chancellery, a smiling Merkel walked her over to a podium where both leaders took their seats. The unusual move came a day after a similar ceremony when the German chancellor was seen shaking involuntarily for the third time in public in less than a month, reviving questions over her health.

Merkel began trembling as national anthems were being played at the reception of Finnish Prime Minister Antti Rinne.

Just over an hour later, she attended a press conference as planned and told journalists that her health was no cause for concern.

She explained that she was simply still in a phase of "processing" a previous shaking spell, but that "there has been progress."

"I will have to live with it for a while," added Merkel, who turns 65 next week.

Medical experts have played down speculation about the shaking episodes, saying there are multiple potential causes of tremor.

Merkel is renowned for her work ethic and has a reputation for outlasting other leaders at EU summits with her ability to focus on the details of complex discussions deep into the night.