Burma opposition leader Aung San Suu Kyi has finally accepted her 1991 Nobel Peace Prize in Oslo.

"Absolute peace in our world is an unattainable goal," Ms Suu Kyi said in her acceptance speech during her first trip to Europe in nearly 25 years.

"Hostilities have not ceased in the far north; to the west, communal violence resulting in arson and murder were taking place just several days before I started out the journey that has brought me here today."

Ms Suu Kyi, the Oxford University-educated daughter of General Aung San, Myanmar's assassinated independence hero, advocated caution about transformation in Myanmar, whose quasi-civilian government continues to hold political prisoners.

"There still remain such prisoners in Burma. It is to be feared that because the best known detainees have been released, the remainder, the unknown ones, will be forgotten," Ms Suu Kyi, 66, told a packed Oslo City Hall.

A day earlier, she arrived from Switzerland to a jubilant reception as dancing and chanting crowds filled Oslo's streets and showered her with flowers.

Ms Suu Kyi, who spent a total of 15 years under house arrest between 1989 and her release in late 2010, never left Myanmar even during brief periods of freedom after 1989, afraid the military would not let her back in.

Her sons, Kim and Alexander, had accepted the Nobel Prize on her behalf in 1991, with her husband Michael Aris also attending the ceremony.

A year later Ms Suu Kyi announced she would use the $1.3 million prize money to establish a health and education trust for Burmese people.

She was unable to be with Mr Aris, an Oxford academic, when he was diagnosed with prostate cancer and died in Britain in 1999.

Last year, the junta surprised the world with reforms that have brought cautious hope for real change, rewarded with visits since by US Secretary of State Hillary Clinton and British Prime Minister David Cameron.

Ex-general President Thein Sein has freed hundreds of political prisoners, welcomed Ms Suu Kyi's party back into mainstream politics, and signed ceasefires with ethnic rebel groups, leading Western nations to ease sanctions.

When she arrived in Oslo yesterday, Ms Suu Kyi warned that "we're certainly not at the end of the road. By no means. We are just starting out."

"And this road is not going to be a straightforward, smooth one. There are going to be many twists and turns and there'll be obstacles. But we'll have to negotiate these in the spirit of national reconciliation."

Ms Suu Kyi's trip has been clouded by ethnic strife at home, regional clashes between majority Buddhists and stateless Muslim Rohingya.

Around 50 people have been killed and scores wounded in the clashes in Rakhine state, state media said, as the UN warned of "immense hardship" faced by thousands displaced by rioting.