The United States on Tuesday walked out of the UN's Conference on Disarmament as Venezuela assumed the body's rotating presidency, with Washington's envoy insisting he would not endure sessions led by "a rogue state."

"What you have going on inside there right now is a diatribe of propaganda," the US ambassador to the conference, Robert Wood, told reporters outside the council's chamber in Geneva.

"Whatever is discussed in there, whatever is decided, has absolutely no legitimacy because it is an illegitimate regime presiding over that body," he added, referring to the government of Venezuelan President Nicolas Maduro.  

Wood walked out immediately after Venezuela's ambassador to the United Nations in Geneva, Jorge Valero, began addressing the conference to begin his presidency. 

The US along with more than 50 other states have recognised Venezuelan opposition leader Juan Guaido as acting president. 

"A representative of Juan Guaido, the interim president, should be in this body, should be sitting in that chair right now," Wood said. 

The Conference on Disarmament was previously a key UN forum for negotiating major arms control pacts. 

But progress in the CD has been blocked for years over a series of diplomatic impasses. 

Wood described the Venezuelan president as "another tragic day in the history of the CD", after Syria last year assumed the body's chair, which rotates on alphabetical order among member states.