Chinese Prime Minister Li Keqiang on Sunday arrived in Moscow for talks with President Vladimir Putin as Russia is struggling with its most pronounced isolation since the end of the Cold War.

"It is a major event in the bilateral relations," Chinese Vice Minister Cheng Guoping said ahead of Li's visit.

He said both sides would sign a joint communique and about 50 agreements. "We are confident it will be a success," he said.

Li's first visit to Russia as premier comes at a sensitive time as the Kremlin is grappling with the consequences of its support for separatists in Ukraine during a six-month conflict in the east of the ex-Soviet country.

Besides meeting Putin on Tuesday, Li during his three-day visit will also meet with his Russian counterpart Dmitry Medvedev and attend an economic forum.

Once bitter foes during the Cold War, Moscow and Beijing have over the past years ramped up cooperation as both are driven by a desire to counterbalance US global dominance.

China and Russia often work in lockstep at the UN Security Council, using their veto power as permanent council members to counter the West on issues such as the Syria crisis.

Russia's showdown with the West over Ukraine has given Kremlin a new impetus to court Beijing.

China for its part has spoken out against the sanctions slapped on Russia by the European Union and the United States to make the Kremlin change tack over Ukraine.

"China always opposes the wilful use of sanctions or the threat of sanctions," said Cheng.

"We welcome the moves by various parties to encourage the momentum of a political settlement of the Ukrainian issue."

Putin late Saturday ordered a pullback of troops from the border with Ukraine and will hold crunch talks with Ukraine's Petro Poroshenko on the sidelines of an Asia-Europe meeting in Milan next week.

Ahead of his Russian visit, Li travelled to Germany for talks with Chancellor Angela Merkel.