Kyiv says it recaptured more than 3,000 square miles this month.

Putin and Xi are attending the Shanghai Cooperation Organisation in Uzbekistan, a grouping of largely authoritarian states seen by some as a growing power bloc rival of the West.

Putin told the Chinese president that Moscow backs Beijing’s “One China” policy, opposes “provocations” by the United States in the Taiwan Strait, and said Russia values China’s “balanced position” on Ukraine.

It is Xi’s first trip outside China since the start of the Covid-19 pandemic.

Putin threw his weight behind Beijing and referred to China’s insistence that other countries do not recognise Taiwan.

“We intend to firmly adhere to the principle of ‘One China’,” Putin said.

He added that Russian “condemns provocations by the United States and their satellites in the Taiwan Strait”.

The United States has no formal diplomatic relations with Taiwan but is bound by law to provide the island with the means to defend itself.

China has never ruled out using force to bring Taiwan under its control.

“In the face of changes in the world, in our times and of history, China is willing to work with Russia to play a leading role in demonstrating the responsibility of major powers, and to instill stability and positive energy into a world in turmoil,” Xi told Putin.

China held blockade-style military drills around Taiwan after US House speaker Nancy Pelosi visited the island last month. Taiwan strongly rejects China’s sovereignty claims.