China has said it opposed any new EU sanctions against Russia over accusations it is fuelling the separatist rebellion in eastern Ukraine.

The European Union announced plans on Sunday to tighten sanctions against the Kremlin, a move that was welcomed by Washington.

Beijing said that the European Union's plan to implement fresh economic penalties against Russia would complicate the crisis.

"A political solution is the only way out, sanctions do not help to solve the underlying problems in Ukraine," said China's foreign ministry spokesman Qin Gang.

"It may lead to new and more complicating factors."

In a bid to remain neutral, China has remained relatively quiet over Russia's behaviour in Ukraine since it annexed the peninsula of Crimea, neither endorsing nor condemning its ally's actions.

Qin called on all parties to "avoid taking further actions that could lead to an escalation of tensions."

The EU and US have imposed a raft of incremental sanctions against Moscow since March. The latest measures, passed in late July, targeted Russia's arms, defence and energy industries.

While sanctions have thwarted economic growth and sparked a rush of capital flight from Russia, they have proved less effective in curbing the violence in eastern Ukraine.

The UN's human rights agency said on August 29 that 2,593 people had been killed since fighting erupted in eastern Ukraine in mid-April, which did not include the 298 people that were killed in the MH17 plane crash.

The death toll rose sharply after Ukraine's President launched an offensive against the pro-Russian separatists that appeared to hamper the rebellion.

However, the separatists appeared to have been re-armed with Russia's assistance in recent weeks, as they fought back against Ukrainian government forces.