By Michael Bristow
BBC News, Beijing
The UN's special envoy for Burma says the nation's plan for a constitutional referendum and multi-party elections is a "significant step".
Mr Gambari has visited Burma twice since the September protests
Ibrahim Gambari said this was the first time the Burmese government had set out a timetable for political reform.
It marked the first "established timeframe for the implementation of (Burma's) political roadmap", he said.
But the UN envoy said the referendum had to be credible and include genuine political participation.
Last week, Burma's military leaders announced that a referendum on a new constitution would be held in May, followed by national elections in 2010.
The main opposition party, the National League for Democracy, was not involved in drafting the constitution, and analysts believe it is likely to bar the party's detained leader, Aung San Suu Kyi, from standing.
Return to Burma
Mr Gambari is in Beijing to enlist Chinese help in persuading Burma to establish a more democratic and open political system.
He spoke to journalists following what he described as "open and constructive" talks with Chinese officials.
During the press conference, Mr Gambari was careful not to suggest China had more influence over Burma than any other country.
But afterwards he admitted China and India were the countries with the most leverage.
Mr Gambari will next visit Indonesia, Singapore and Japan as part of his efforts to push forward reform in Burma.
He was last in Burma in November last year, but said he hoped to return before April.
"The authorities had said they would receive me after the middle of April, but we have reason to believe they are reconsidering," he said.
Although the envoy said he was not frustrated by the apparent lack of progress, he added that there needed to be tangible results.
These included lifting restrictions on Ms Suu Kyi, who is under house arrest, and establishing a more inclusive political system.
The UN envoy has been working on a political settlement since Burmese troops used force to end anti-government protests in September last year.