Aung San Suu Kyi's doctor expressed worry Friday that the Nobel Peace laureate's whirlwind tour of Europe could weaken her health, after she fell ill on the second day of her two-week trip.

The 66-year-old opposition leader known for her steely grace and longtime struggle for democracy in Burma has a weak stomach when it comes to travel, said Pyone Moe Ei, one of Suu Kyi's two personal physicians. Suu Kyi had similar bouts with weakness and vomiting during her rigorous nationwide campaign for a seat in Parliament earlier this year, which doctors attributed to exhaustion and motion sickness.

"I am very concerned for her health," Pyone told The Associated Press in Rangoon. "Considering her age, the amount of travel she's doing, the time difference, lack of rest and her extremely tight schedule — it is very worrisome."

Suu Kyi arrived late Wednesday night in Switzerland, on her first trip to Europe in 24 years. Her high-profile visit also includes stops in Norway, Ireland, England and France.

Thursday's hectic schedule included speeches, receptions and news conferences first in Geneva and then in the Swiss capital Bern, where Suu Kyi looked pale and told reporters she felt exhausted. At one point she pressed a finger to her lips and motioned to an aide who rushed to her side with a bag. She then bent over and threw up before being escorted out of the room.

Resumed her schedule

Suu Kyi cancelled an evening dinner in Bern but resumed her schedule Friday with a visit to the Swiss parliament. A highlight of her trip is expected Saturday, when she will be in Norway to formally accept her Nobel Peace Prize 21 years late.

Suu Kyi's doctor said she has no serious health problems but weighs a mere 48 kilograms, has low blood pressure and can get easily weakened by vomiting. Pyone said she had not spoken directly to Suu Kyi after her ill spell in Bern but had been in contact with people close to her. It was not immediately known what treatment, if any, Suu Kyi received.

Doctors in Burma — which is also known as Myanmar —had placed Suu Kyi on intravenous drips after motion sickness caused her to fall ill twice during her campaign in March.

The European trip is seen as a sign of gratitude to governments and organizations that supported Suu Kyi's peaceful struggle against Burma's former military rulers over more than two decades, 15 years of which she spent under house arrest.

Last month, Suu Kyi made her first trip out of Burma in 24 years to neighbouring Thailand. Ahead of that trip, aides said she was preparing by packing her medicine for motion sickness.