United Nations Secretary General Kofi Annan has called for Burma's opposition leader Aung San Suu Kyi to be freed from house arrest.
Aung San Suu Kyi has been detained for more than a year
He said the Burmese government's reforms would not be credible without the involvement of Aung San Suu Kyi's National League for Democracy.
He called for "substantive dialogue" between all parties.
He released a statement after Aung San Suu Kyi's party failed in an attempt to win her release.
A spokesman for the NLD said the legal bid failed because officials refused to sign a document presented to the court.
The government of Burma - called Myanmar by its ruling military junta - last month adjourned a national convention meant to draw up a new constitution as a first step to the restoration of democracy.
It had promised to welcome all religious and political parties into the process, but has been criticised for hand-picking most of the delegates.
The NLD is refusing to take part in the process until Aung San Suu Kyi is freed.
Mr Annan's statement said: "Unless and until the views of the National League for Democracy and other political parties are sought and considered, the
national convention and the roadmap process will be incomplete, lacking in credibility, and therefore unable to gain the full support of the international community, including the countries of the region."
Mr Annan also urged the Burmese government to allow his special envoy, Razali Ismail, to return to the country and help the transition towards democracy.
Earlier this year the authorities rejected Mr Razali's visa application.
Democratic elections were last held in Burma in 1990. The NLD overwhelmingly won the vote, which was then ignored by the military, which has ruled the country since 1962.
On Sunday the US urged Burma to release Aung San Suu Kyi and reform its political