Russian President Vladimir Putin on Thursday blasted attempts to create a "unipolar world" and praised China's "balanced" approach to Ukraine, as he met Chinese President Xi Jinping in Uzbekistan.

Holding their first in-person talks since the start of the Ukraine conflict, Putin took a clear broadside at the United States, saying: "Attempts to create a unipolar world have recently acquired an absolutely ugly form and are completely unacceptable."

Putin and Xi sat across from each other at the centres of two long rounded tables, flanked by their delegations on either side, as they met on the sidelines of a summit of the Shanghai Cooperation Organisation (SCO) in the Uzbek city of Samarkand.

They appeared to be the only two of the about two dozen people in the room not wearing face masks.

"We highly appreciate the balanced position of our Chinese friends in connection with the Ukrainian crisis," Putin told Xi.

"We understand your concerns," Putin said, without specifying what issues China may have raised about Ukraine.

"For our part, we adhere to the principle of one China. We condemn the provocation of the US and their satellites in the Taiwan Strait," Putin said.

Putin called for the "global strengthening of the SCO" and said he was sure Thursday's meeting would help in "strengthening the Russian-Chinese partnership".