UNITED NATIONS (AFP) - Bolivia's outspoken President Evo Morales has urged that UN headquarters be moved from New York because of US "blackmail" and bullying.

Socialist Morales lashed out at the US government for its handling of Venezuelan counterpart Nicolas Maduro and blasted American "imperialism" during a fiery 40-minute speech to the UN General Assembly.

"We must seriously think about changing the headquarters of the United Nations," said Mr Morales, a flag bearer for Latin America's left wing leaders after the death of Venezuela's Hugo Chavez.

"The headquarters should be in a state that has ratified all UN treaties," Mr Morales added.

"How can we be safe at a meeting of the United Nations here in New York? Maybe not all," he added.

"Some do not believe in imperialism and capitalism and feel totally unsafe," Mr Morales said, referring to Mr Maduro's battle with US authorities over his attendance at the annual UN leaders' summit.

Mr Morales expressed "solidarity" with the Venezuelan president who accused the United States of refusing him permission to fly through US airspace on a trip to China as well as some visas for his staff to go to the UN assembly.

Mr Maduro had been scheduled to speak at the UN assembly on Wednesday, but pulled out of the visit.

The US administration said an application for the airspace flight was badly filled in and denied that any visas were refused.

"No guaranteed visas, no guaranteed overflights. We feel threatened, bullied and blackmailed over visas," he said, adding that the United States "has never ratified treaties related to human rights."

Mr Morales said he did not think his native Bolivia nor Latin America could handle the UN headquarters.

The UN headquarters has been in New York since the global body's creation in 1945. It moved into its 18 acre complex overlooking the East River in 1952.