The United States indirectly criticized China on Monday for shielding Myanmar from strong UN Security Council action over a military crackdown against mainly Rohingya Muslims that the US and other countries have denounced as ethnic cleansing.

US Ambassador Nikki Haley did not mention China by name, but China proposed substantial amendments to a British-drafted Security Council statement on Myanmar last week. The 15-member council eventually agreed a weaker statement.

The Security Council met on Monday to discuss a visit by envoys to Myanmar and Bangladesh two weeks ago.

Rohingya insurgent attacks on security posts in Myanmar's Rakhine state in August last year sparked a military operation that sent nearly 700,000 Rohingya fleeing to camps in Cox's Bazar in Bangladesh.

"Some members of the council have kept us from taking action for cynical and self-interested reasons," Haley said. "Some undermined the unity of the council demonstrated during the trip with unhelpful edits that only weakened the council's message."

Speaking before Haley, China's UN Ambassador Ma Zhaoxu told the Security Council that Myanmar and Bangladesh should be encouraged to solve the crisis bilaterally to make sure it doesn't "drag on or become more complicated."

"The council should continue to encourage Myanmar and Bangladesh to increase consultations and cooperation for the early implementation of the bilateral arrangement," he said.

Myanmar and Bangladesh agreed in January to complete the voluntary repatriation of the refugees within two years but differences between the two sides remain and implementation of the plan has been slow.

Diplomats said Russia has also backed China in council discussions on Myanmar.

Speaking after Haley, Russia's deputy UN Ambassador Dmitry Polyanskiy said the unity of the council on the issue was important and he hoped some members "will not fall prey to the temptation of using this situation to pursue their narrow, domestic political aims."

Fleeing refugees have reported killings, rapes and arson on a large scale. Myanmar denies ethnic cleansing and has said its operations in Rakhine were a legitimate response to attacks on security forces by Rohingya insurgents.

"The government of Myanmar has stated time and again that no violation of human rights will be condoned," Myanmar's UN Ambassador Hau Do Suan told council on Monday. "Allegations supported by evidence will be investigated and action taken in accordance with the law."

The United States and Canada have imposed unilateral sanctions against a general in Myanmar's military for his role in the crackdown and the European Union is preparing individual sanctions.

Haley, who did not travel to Myanmar and Bangladesh, said that the Security Council had "unique tools to encourage Burma to take real steps towards resolving this crisis," though she did not elaborate.

"We should move quickly to adopt a resolution that institutes real steps to resolve this enormous and growing humanitarian and human rights crisis," Haley said.