The letter, released through Myanmar exiles and democracy campaigners in the United States, berates the Yangon junta for ignoring previous UN General Assembly and Commission on Human Rights resolutions.

"Now is the time for UN Secretary-General Kofi Annan and members of the UN Security Council to move beyond discussion and take action," the groups said in a statement accompanying the letter.

"The situation for Burma's 53 million people grows more desperate and horrific each day."

A UN Security Council resolution should call on Myanmar's rulers to protect and help their people, demand an end to military attacks on ethnic minorities, and mandate immediate access for humanitarian agencies into the country, the letter said.

It would also call on the junta to work towards political reconciliation, 16 years after unleashing political turmoil by refusing to accept the landslide election win of Aung San Suu Kyi's National League for Democracy (NLD).

The United States has been lobbying hard for an unprecedented Security Council resolution.

The council held its first-ever meeting on human rights abuses and other problems in Myanmar last December at Washington's urging.

Aung San Suu Kyi, 61, has spent 10 of the past 17 years in detention at her lakeside home in Yangon.

The letter was signed by organisations from states and territories including the United States, France, Hong Kong, Malaysia, the Czech Republic, South Korea, Canada and Poland.

They included groups like FORUM-ASIA, based in Thailand, Reporters Without Borders and the US Campaign for Burma.