By Laurie Chen and Vladimir Soldatkin

BEIJING President Vladimir Putin on Wednesday praised Chinese President Xi Jinping for the Belt and Road Initiative (BRI) and invited global investment in the Northern Sea route which he said could deepen trade between east and west.

Speaking on his second known trip outside the former Soviet Union since the Ukraine war, Putin thanked the Chinese leader for his invitation and said Russia could play a key role in China's modern day revival of the ancient Silk Road.

Putin called Xi his "dear friend" and heaped praise on the Belt and Road Initiative for bringing the world together.

Shortly before Putin starting speaking, a handful of European delegates, including former French Prime Minister Jean-Pierre Raffarin, walked out of the room, a Reuters witness said.

"Russia and China, like most countries of the world, share the desire for equal, mutually beneficial cooperation in order to achieve universal sustainable and long-term economic progress and social well-being, while respecting the diversity of civilization and the right of each State to its own development model," Putin said.

Putin said the BRI fitted with Russia which he said was developing a host of transport infrastructure to criss-cross the world's biggest country, notably from the Northern Sea Route which runs from Murmansk near Russia's border with Norway eastwards to the Bering Strait near Alaska

"As for the Northern Sea Route, Russia does not just offer its partners to actively use its transit potential, I will say more: we invite interested states to participate directly in its development, and we are ready to provide reliable ice breaker navigation, communication and supply," Putin said.

"Starting next year, navigation for ice-class cargo ships along the entire length of the Northern Sea Route will become year-round."

Putin, who has attended previous BRI summits, brought a senior delegation from Moscow.

Among the senior Russian officials were Foreign Minister Sergei Lavrov, who is due to visit North Korea shortly, Deputy Prime Minister Alexander Novak, his top oil and gas point man, and Deputy Prime Minister Dmitry Chernyshenko.

Also included were Kremlin spokesman Dmitry Peskov, Kremlin economic aide Maxim Oreshkin, Kremlin foreign policy aide Yuri Ushakov, Economy Minister Maxim Reshetnikov and Igor Morgulov, Russia's ambassador to China.

(Reporting by Vladimir Soldatkin in Moscow and Laurie Chen in Beijing; Editing by Guy Faulconbridge)