Activists are marking the 12th year of detention for Burmese democracy leader Aung San Suu Kyi, in a series of protests taking place in 12 cities.
Protesters wore masks of Ms Suu Kyi's face during the demos
Campaigners are targeting Chinese embassies, as they say Beijing holds the key to Ms Suu Kyi's release.
The Nobel Peace Prize winner has been held by Burma's military junta, mostly under house arrest, for 12 of the past 18 years.
Meanwhile, Australia has announced sanctions against Burma's rulers.
Canberra said the measures would target 418 individuals, including top military figures and cabinet ministers.
Pressure has been growing on the military junta since its bloody suppression of pro-democracy protests last month.
The generals have agreed to another visit from the UN's special envoy Ibrahim Gambari, who is currently in China lobbying for Beijing's backing for democratic reforms in Burma.
And they are also allowing the UN's human rights investigator, Paulo Sergio Pinheiro, to visit the country for the first time in four years. He is due to speak in New York later.
In the Thai capital, Bangkok, a small group of activists gathered outside the Chinese embassy, dressed in chains and wearing masks of Ms Suu Kyi, chanting: "Free, free, Aung San Suu Kyi."
SUU KYI APPEAL
Open letter signed by Nobel peace laureates Jody Williams, Shirin Ebadi, Wangari Maathai, Rigoberta Menchu Tum, Betty Williams and Mairead Corrigan Maguire
Rallies in London, Paris, Berlin, Dublin, Vienna, Sydney, Washington, Toronto, New York, Brasilia, Bangkok and Cape Town
Other cities involved in the protests include London, Paris, Brasilia, New York, and Cape Town.
Six female Nobel peace laureates have jointly appealed to the UN, urging it to help Ms Suu Kyi regain her freedom.
"The detention of Aung San Suu Kyi is the most visible manifestation of the regime's brutality but it is only the tip of the iceberg," they wrote in an open letter published in UK newspaper The Guardian.
Ms Suu Kyi's National League for Democracy won a convincing victory in a general election in 1990 but the junta refused to hand over power.
The protests coincide with the anniversary of the UN charter, and campaigners say they will be stepping up the pressure for UN action.
They blame China for blocking a UN resolution against Burma's generals.
Mr Gambari, who is expected to return to Burma next month, is meeting senior Chinese officials this week.
But he will not see any of the country's top leaders, the BBC's Daniel Griffiths reports from Beijing.
Although China, one of Burma's closest allies, has expressed concern about the situation there, it has always stressed that it will not interfere in its neighbour's internal affairs.
It is a sign that Beijing is unwilling to push Burma too hard, our correspondent says.
Burmese officials say 10 people died during the crackdown on protests in September, but diplomats believe the true figures are much higher. Hundreds of people are thought to be in detention.