China, Russia and European powers, all of which signed the 2015 Iran nuclear accord, are scrambling to save the pact following the US president's decision to quit the agreement and reinstate sanctions.

China's President Xi Jinping will meet Iran's Hassan Rouhani on the sidelines of the Shanghai Cooperation Organisation (SCO) meeting from June 9-10 in Qingdao, said Chinese Foreign Minister Wang Yi.

Russian President Vladimir Putin will also attend the summit, he added.

Wang did not include the nuclear deal in a readout of the summit's formal agenda.

But Beijing, which is already Iran's top trade partner and one of its biggest buyers of crude, has signalled that it intends to keep working with the Islamic regime despite the US move.

Chinese businesses are expected to step up activities in Iran to fill the void left by the exit of US companies and the possible withdrawal of European rivals amid punitive measures enforced by the US.

Iran is currently an observer member of the SCO, though it has long sought full membership.

The regional bloc focusing on security and trade also includes four ex-Soviet central Asian republics and two new members, Pakistan and India.