His comments on Tuesday came hours after US President Joe Biden said he didn't have any intention of starting a "new Cold War" - itself a response to criticism from the UN chief that both Washington and Beijing need to make sure their differences and tensions don't derail their 42-year-old relationship.

"One country's success does not have to mean another country's failure," Xi said in a prerecorded speech.

"The world is big enough to accommodate common development and progress of all countries."

The comments from leaders of the two major powers, the world's most formidable economies, appeared to represent efforts to calm the waters after UN Secretary-General Antonio Guterres admonished them over the weekend for putting confrontation over productive dialogue.

China often preaches multilateralism, though its critics say its policies toward Taiwan and in South China Sea territorial disputes strongly indicate otherwise. Without mentioning the US directly, he said "military intervention from the outside and so-called democratic transformation entail nothing but harm."

"We need to pursue dialogue and inclusiveness over confrontation and exclusion," he said.

The very presence of a Xi speech was unexpected. Earlier schedules of UN speakers indicated a deputy Chinese premier would give an address Friday afternoon.

The decision to slot in the country's supreme leader moved him up to Tuesday's first-day slate, hours after Biden's remarks.

Australian Associated Press