German Chancellor Angela Merkel was seen shaking as she met President Frank-Walter Steinmeier on Thursday, her second such bout within two weeks, but her spokesman said she was fine and she headed off to Japan for this weekend's G20 summit.

Merkel, 64, has no history of serious health issues. She was attending a farewell ceremony for Justice Minister Katarina Barley, who is leaving to become a lawmaker in the European Parliament, when the incident occurred.

Standing next to Steinmeier as he addressed the gathering, Merkel started shaking visibly in her upper body, then crossed her arms as if to brace herself. She was offered a glass of water but declined to drink it while Steinmeier spoke.

Berlin is in the throes of a heatwave.

Another government official said that while Merkel attributed the tremors on June 18 to drinking too little water and too much coffee on a hot day, Thursday's episode was more a psychological issue as she tried desperately to avoid a repeat.

"The memory of the incident last week led to the situation today - so (it was) a psychologically driven process," the official said. "There is nothing to worry about."

Merkel was seen shaking when she met visiting Ukrainian President Volodymyr Zelenskiy on June 18 but later said she felt better after drinking some water.

Asked about Merkel's latest shaking episode, Interior Minister Horst Seehofer told reporters: "I won't comment on this. I have never taken part in remote diagnoses because for years I was too often the subject of remote diagnoses."

Appeals to her right for privacy were not enough for some newspapers. "On her health rides the effectiveness of her government and the stability of her country," wrote the conservative Die Welt in a commentary. Her health, it said, is "not purely a private matter."

Merkel began a stage-managed gradual exit from politics in October.