Defence Minister Dong Jun on Thursday urged greater efforts for global unity, warning against an increasingly divided world "defined by the rule of the jungle".

Speaking to formally open the Beijing Xiangshan Forum on security, Dong warned of "new threats and challenges" now facing world peace.

"While the themes of the times – peace and development – remain unchanged, the clouds of a Cold War mentality, hegemonism and protectionism have not lifted," he said.

"External military interference, seeking spheres of influence and coercing others to take sides will bring the international community into chaos," Dong said, adding that the world was at another "crossroads" and had to choose dialogue over confrontation.

"An obsession with absolute superiority in military strength and a 'might is right' approach will lead to a divided world defined by the rule of the jungle and disorder," Dong said. A strong Chinese military would be a force for peace, he added.

The defence chief also said China's safeguarding of "territorial sovereignty and maritime rights and interests... is a firm defence of the post-war order and international rule of law".

"The so-called freedom of navigation advocated by certain countries outside the region and the so-called international arbitration advocated by certain claimants blatantly challenge the fundamental norms of international relations," Dong said.

The minister added that the People's Liberation Army would never allow any Taiwan separatist attempts to succeed, and it was ready "to thwart external military interference at all times".

Some 1,800 representatives from 100 countries, including officials, military personnel and scholars, are attending the annual three-day event, the Xinhua news agency reported.

The forum ends on Friday. (Agencies)