Elections in Burma will not be "credible" without pro-democracy leader Aung San Suu Kyi, according to United Nations Secretary-General Ban Ki-Moon.
"To be credible and legitimate, Aung San Suu Kyi and all political prisoners should be released," he said.
Mr Ban said that, during his recent two-day visit to the country, he made it clear to the top military leader, General Than Shwe, "what is expected of Burma's leaders on several issues, and now it was up to them to respond positively".
"I emphasised that, without participation of Aung San Suu Kyi, without her being able to campaign freely, and without her NLD party (being able) to establish party offices all throughout the provinces, this election may not be regarded as credible and legitimate," he said in New York.
National elections are due to take place next year.
Members of the UN Security Council, including Britain, US and France, have expressed their concerns over the imprisonment of Ms Suu Kyi, who has been under house arrest for more than 13 of the last 19 years.
During his visit, Mr Ban was not allowed to meet Ms Suu Kyi.
"The refusal of the senior leadership to allow me to meet Ms Suu Kyi was not only a deep disappointment, but also a major lost opportunity for Burma," Mr Ban said.
Ms Suu Kyi is currently facing trial for violating the conditions of her restriction order, which bans visitors without official permission. The offence is punishable by up to five years' imprisonment.
The Secretary-General added that he had urged Burma's senior leadership to enhance co-operation with the UN to improve socio-economic development and to empower the people to participate more in their country's development.