Beijing is strengthening its multilateral platforms to play a bigger role in shaping the world order, as the United States and an expanding Nato move to counter challenges from China.

Beijing officials called on the China-led Shanghai Cooperation Organisation (SCO) to oppose hegemony and confrontations between blocs during a round-table discussion to mark the 20th anniversary of the signing of the group's charter on Wednesday.

Chinese Foreign Minister Wang Yi urged the regional security bloc's member countries to strengthen unity and cooperation, firmly oppose external interference, and continue to show "solid support" for each other's development.

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Wang said China was willing to work with member states to "oppose hegemonic bullying, resolutely resist the Cold War mentality" and promote the democratisation of international relations.

SCO Secretary General Zhang Ming said the group should reform and improve itself and have the "courage to exert positive energy on the international stage".

Iran is expected to officially become the ninth member of the SCO at the group's summit in September, wrapping up an accession process that started last year. It will be the first expansion of the group since India and Pakistan joined in 2017.

Muhammad Hassan Shekholeslami, president of the Institute for Political and International Studies, a Tehran-based think tank, said Iran will bring potential and opportunity to the group because of its geographical advantages and rich energy and human resources.

On June 25, Belarus President Aleksandr Lukashenko asked for Russia's support in upgrading his country's status within the SCO, where it is currently an observer.

The BRICS bloc, which includes the emerging markets of Brazil, Russia, India, China, and South Africa, is also on a fast track to expanding its membership.

Argentina and Iran have applied to join BRICS, Russian foreign ministry spokeswoman Maria Zakharova said on Monday. "While the White House was thinking what to disconnect, ban or spoil in the world, Argentina and Iran have applied for joining BRICS," she wrote on her Telegram channel.

The development came as China was labelled a "challenge" by Nato in its strategic blueprint, while Russia, also a member of the SCO, was targeted as the "most significant and direct threat to the allies' security". Nato adopted the blueprint on Wednesday during its summit in Madrid.