The Shanghai Cooperation Organisation, comprising China, India, Russia, Pakistan, Iran, Kazakhstan, Kyrgyzstan, Tajikistan, Uzbekistan and Belarus, is touted as a non-Western style of collaboration and seeks to be an alternative to traditional alliances.

Xi told the SCO leaders, including Russian and Belarusian presidents Vladimir Putin and Alexander Lukashenko, that the global international situation was becoming more "chaotic and intertwined".

The Chinese leader also slammed "bullying behaviour" from certain countries -- a veiled reference to the United States.

"The security and development tasks facing member states have become even more challenging," he added in his address to all the gathered dignitaries in the northern port city of Tianjin.

"Looking to the future, with the world undergoing turbulence and transformation, we must continue to follow the Shanghai spirit... and better perform the functions of the organisation," Xi said.

Leaders from the ten SCO countries including Putin, Lukashenko and India's Prime Minister Narendra Modi arrived earlier on a red carpet and posed for a group photo.

Xi, Putin and Modi were seen chatting on live footage, the three leaders flanked by their official translators.

The SCO summit, which also involves 16 more countries as observers or "dialogue partners", kicked off on Sunday, days before a massive military parade in the capital Beijing to mark 80 years since the end of World War II.

- Putin, Modi -

Putin touched down in Tianjin on Sunday with an entourage of senior politicians and business representatives.

Xi held a flurry of back-to-back bilateral meetings with leaders including Lukashenko -- one of Putin's staunch allies -- and Modi who is on his first visit to China since 2018.

Modi told Xi that India was committed to taking "forward our ties on the basis of mutual trust, dignity and sensitivity".

The two most populous nations are intense rivals competing for influence across South Asia and fought a deadly border clash in 2020.

A thaw began last October, when Modi met with Xi for the first time in five years at a summit in Russia.

Their rapprochement deepened as US President Donald Trump pressured both Asian economic giants with trade tariffs.

- 'Mutual benefit' -

China and Russia have sometimes promoted the SCO as an alternative to organisations like NATO. This year's summit is the first since Trump returned to the White House.

Official posters promoting the SCO lined Tianjin's streets, displaying words such as "mutual benefit" and "equality" written in Chinese and Russian.

More than 20 leaders including Iranian President Masoud Pezeshkian and his Turkish counterpart Recep Tayyip Erdogan are attending the bloc's largest meeting since its founding in 2001.

Putin is expected to hold talks on Monday with Erdogan and Pezeshkian about the Ukraine conflict and Tehran's nuclear programme respectively.

Many of the assembled dignitaries will be in Beijing on Wednesday to witness the military parade, which will also be attended by North Korean leader Kim Jong Un.