German Chancellor Angela Merkel remained seated for national anthems at an official ceremony Tuesday for the second time in a week, after a series of shaking spells sparked concern about her health.

(File photo:VCG)

Merkel took a seat next to visiting Moldovan Prime Minister Maia Sandu during military honours for her guest, one day before the German leader's 65th birthday.

She has suffered three bouts of uncontrolled shaking while standing at public ceremonies, and remained seated last week as national anthems were played during a ceremony with Denmark's new prime minister.

However the German chancellor insists she is doing "very well" and there is no need to be alarmed about her wellbeing.

She has kept up a gruelling schedule since her first trembling spell a month ago including attending a G20 gathering in Japan followed by a crunch EU summit in Brussels.

Merkel is expected to embark on her annual summer holiday later this month.

A poll published at the weekend indicated that 59 percent of Germans saw the shaking as Merkel's "private" matter, while 34 percent said it was a matter of public interest.

Merkel has been in power since 2005 and plans to step down at the end of her fourth term, in 2021.