A senior Russian lawmaker said on Wednesday that Moscow must start arming Ukraine's separatist-held regions to help them defend themselves against the Western-backed Kyiv authorities.

In a statement broadcast on Russia's state TV Andrei Turchak, first deputy speaker of the Federation Council, Russia's upper house of parliament, said:

"Russia must provide the Lugansk and Donetsk People's Republics with necessary assistance by sending them certain types of weapons to ramp up their defense capability and deter a military aggression clearly being prepared by Kyiv."

The United States and its EU allies accuse Russia of seeking to upend European stability by threatening an invasion of Ukraine, a former Soviet republic striving to join NATO and other Western institutions.

Moscow denies plans to invade the country, where in addition to annexing Crimea, it has been backing separatist forces in the east since 2014. The conflict has already claimed more than 13,000 lives.

The West and Kyiv accuse Moscow of fuelling an insurgency by sending weapons and troops across the border. 

Russia has always denied such claims, and Turchak's statement on Wednesday could mark a change in Moscow's official stance.

Turchak, who is secretary of the general council of the ruling United Russia party, did not specify what types of weapons should be sent to Ukrainian separatists.

But he added that the ruling party was concerned by the escalation of tension and supply of Western arms to Kyiv.

"Civilians are dying," he said in televised remarks.

"Western patrons are pushing the Ukrainian junta towards a direct invasion of the Donbass," he said, referring to the name for the two breakaway regions.

"The Kyiv regime must be stopped."

Kyiv this month accused Russia of carrying out a sweeping cyberattack on government websites while Britain said it had evidence of a Russian plot to install pro-Kremlin leadership in Ukraine.