The UN has criticised a lack of progress in Burma towards change, after last year's violent suppression of anti-government protests.
At least 31 people died when troops suppressed protests last year
The UN Security Council called for more dialogue between Burma's military government and pro-democracy leaders.
It also urged the ruling junta to allow another visit by UN envoy Ibrahim Gambari.
He has visited Burma twice since September's violence, in which at least 31 people were killed.
In December, human rights rapporteur Paulo Sergio Pinheiro said more than 600 people were still being detained by the authorities as a result of the protests.
In the wake of the violence, the UN called for genuine dialogue between the junta and the Aung San Suu Kyi-led pro-democracy movement, and the release of political prisoners.
In its statement, the council said it "regretted the slow rate of progress so far toward meeting those objectives".
A Burmese government liaison, Aung Kyi, has so far held four meetings with the detained Ms Suu Kyi, but with little apparent progress.
Mr Gambari said he wanted leaders to allow him to visit the country later this month.
They had told him "that it's not convenient and they will prefer mid-April", he told reporters at the UN.
This was unacceptable and the UN was now in the process of negotiating "an earlier, rather than a later" return to Burma, he said.
US envoy to the UN Zalmay Khalilzad said that the organisation needed to do more to confront Burma's leaders.
"There is a huge gap between where we need to be and where we are," he said.
"The policy of both engagement on the one hand with Mr Gambari and pressure on the other hand, and preparedness to increase the pressure as appropriate, is the right mix."
September's protests followed an unexpected hike in the price of fuel, hitting people hard in the poverty-stricken nation.
Pro-democracy activists began the movement, which escalated into a huge monk-led demonstration against the ruling junta.
Government troops used force to end the protests.