Wednesday's showcase of China's might has been seized by world leaders as an opportunity to hold rare face-to-face talks, with North Korea's Kim Jong Un expected to hold summits with both Putin and Xi according to South Korean sources.

Xi himself has embarked on a flurry of diplomatic meetings this week, including attendance at the Shanghai Cooperation Organisation (SCO) summit in the northern city of Tianjin -- a forum that China sees as an alternative to Western-dominated international cooperation.

Meeting Xi on Tuesday, Putin told him "our close communication reflects the strategic nature of Russian-Chinese ties, which are currently at an unprecedented level", according to a pooled live feed.

In a nod to cooperation between the two countries during the war, Putin said "we were always together then, and we remain together now".

The military parade on Wednesday marks 80 years since the end of World War II and will be attended by around two dozen world leaders, including Kim in his first visit to China since 2019.

Kim is expected to mingle with other world leaders at a gala performance, as well as meet Xi and Putin for talks, Lee Seong-kweun, a South Korean member of parliament briefed by Seoul's spy agency, told reporters.

Putin is also expected to meet with Slovakian Prime Minister Robert Fico.

Fico has irked European leaders by criticising the bloc's support for Ukraine and pushing back against efforts to cut energy imports from Russia. Slovakia is highly reliant on Russian gas.

- Global turmoil -

The Chinese and Russian leaders criticised Western governments during the summit on Monday, where Xi slammed "bullying behaviour" from certain countries -- a veiled reference to the United States, while Putin defended Russia's Ukraine offensive and blamed the West for triggering the conflict.

"China-Russia relations have withstood the test of international changes," Xi told Putin on Tuesday.

Xi added that Beijing was willing to work with Moscow to "promote the construction of a more just and reasonable global governance system".

The two leaders are in regular contact, and in May, Xi visited Moscow for Russia's celebrations of the World War II defeat of the Nazis.

Moscow and Beijing declared a "no limits partnership" shortly before Putin ordered Russia's Ukraine offensive in February 2022. The expanded military and trade ties since have troubled the West.

On Tuesday Russian state media reported that energy giant Gazprom had struck a deal with China National Petroleum Corporation to boost gas supplies from Russia to China by about 15 percent.

China has never denounced Russia's war nor called for it to withdraw its troops, and many of Ukraine's allies believe that Beijing has provided support to Moscow.

Beijing insists it is a neutral party, regularly calling for an end to the fighting while also accusing Western countries of prolonging the conflict by arming Ukraine.

North Korea, meanwhile, has thrown itself firmly behind Moscow, sending troops to help fight Ukraine.

Around 2,000 North Koreans are estimated to have been killed in the conflict, Seoul's spy agency said Tuesday, according to lawmaker Lee.