Former Russian president Dmitry Medvedev has undertaken a surprise trip to Beijing and held talks with Chinese President Xi Jinping during which he said they discussed the Ukraine conflict.

Medvedev, now deputy chairman of Russia's Security Council, posted a video on his Telegram channel showing him meeting Xi, smiling for photos and a meeting between Chinese and Russian officials.

Medvedev said he and Xi had discussed the two countries' "no limits" strategic partnership, as well as Ukraine. He did not provide further details.

"We discussed cooperation between the two ruling parties of China and Russia ... bilateral cooperation within our strategic partnership, including on the economy and industrial production. We also discussed international issues - including, of course, the conflict in Ukraine," Medvedev said.

"The talks were useful," he added.

Russia accelerated its pivot towards Beijing after it was hit with a slew of Western sanctions to punish it for its February invasion of Ukraine, something Moscow calls "a special military operation."

Russia is seeking to foster closer economic, political and security ties with China to offset its loss of comparable Western ties and sees Xi as a potential ally in an anti-Western coalition. (Reporting by Reuters Editing by Andrew Osborn)