China is hosting diplomats from Iran and Russia for talks on Tehran’s nuclear program Friday as Beijing aims to position itself as a power broker on an issue seen internationally as a pressing security concern.

China and Russia stood by Iran on Friday after the United States demanded nuclear talks with Tehran, with senior Chinese and Russian diplomats saying dialogue should only resume based on "mutual respect" and all sanctions ought to be lifted.

The US president says he has proposed talks on a deal to prevent Iran acquiring nuclear weapons and to avert military action.