The Organisation of American States has passed a motion backing the "inviolability of diplomatic missions", amid a row between Britain and Ecuador over Wikileaks founder Julian Assange.
The meeting was called by Ecuador which accused Britain of threatening to storm its Embassy in London.
Britain insisted it had made no threat. The United States withdrew its opposition to the resolution after the text was amended to express solidarity with Ecuador, with no reference to any threat against its embassy in London.
Ecuador announced on 16 August that it had granted Mr Assange, 41, asylum.
He took refuge in the Ecuadorian Embassy in London in May to avoid deportation to Sweden to face accusations of sexual abuse.
He says he fears he will then be passed on to the United States.
Britain has said it will follow its obligations under the Extradition Act to arrest Mr Assange if he leaves the Embassy.
The OAS represents 35 states in the Caribbean and North and South America.