A 193-member UN General Assembly vote on Tuesday on a draft resolution calling "for an immediate suspension of the direct and indirect supply, sale or transfer of all weapons and munitions" to Myanmar has been postponed, diplomats said.
A spokesman for the UN General Assembly president said earlier on Monday that the body was due to vote on Tuesday. It was not immediately known when a vote would be rescheduled. Some diplomats said it had been delayed in a bid to win more support.
The draft resolution calls on the Myanmar military - which seized power in a Feb. 1 coup - to end a state of emergency, stop all violence against peaceful protesters and respect the will of the people as expressed in the results of a November election.
General Assembly resolutions are not legally binding but carry political weight. Unlike the 15-member Security Council, no country has a veto power in the General Assembly.
Myanmar has been in crisis since the army ousted leader Aung San Suu Kyi's elected government and detained her and officials of her National League for Democracy party. The UN draft text calls for their release.
The military, which has set up a ruling junta of generals, complained of fraud in the November election that returned Suu Kyi to power. The election commission said the vote was fair.
The draft General Assembly resolution "calls upon the Myanmar armed forces to immediately stop all violence against peaceful demonstrators, members of civil society, women, youth, as well as children and others."
At least 788 people have been killed by the junta's security forces in crackdowns on protests against its rule, according to an advocacy group.
The military, which disputes that number, imposes tight restrictions on media, information and the internet. Reuters cannot independently verify arrests and casualty numbers.
The UN text also urges the army to stop "attacks on, harassment of and restrictions on medical personnel, human rights defenders, labor union members, journalists and media workers ... and restrictions on the internet and social media".
If adopted, the draft resolution would urge the military to allow a visit by the UN special envoy on Myanmar, Christine Schraner Burgener, and implement a plan by the Association of Southeast Asian Nations (ASEAN) to end the crisis.
The United States, Britain and Canada on Monday imposed new sanctions targeting Myanmar's junta.
Only the UN Security Council can impose legally binding sanctions or an arms embargo, but diplomats say Russia and China could likely use their veto to prevent such action on Myanmar.