A pro-Russian journalist was shot dead in Ukraine's capital Thursday, leading Kiev to brand the latest murders of pro-Moscow figures an enemy "provocation".

Columnist Oles Buzyna, 45, a supporter of Ukraine's ousted Kremlin-backed president Viktor Yanukovych, was gunned down in central Kiev by an unknown assailant just hours after the slaying of former ruling party lawmaker Oleg Kalashnikov in the city.

Ukraine's government said the killings of its opponents was aimed at destabilising the country as it battles pro-Russian separatists in the east in a conflict that has killed more than 6,000 people.

An AFP photographer saw Buzyna's bloody body lying on the ground near a playground in the centre of the capital surrounded by police officers after the shooting.

Police found Kalashnikov shot dead at his home in Kiev Wednesday evening.

The killings follow a spate of suspicious deaths of former Yanukovych allies in February and March that raised suspicions among critics that the pro-EU government's opponents were being persecuted.

President Petro Poroshenko called the latest killings "a deliberate provocation which plays into the hands of our enemies, destabilising the political situation in Ukraine".

Russian President Vladimir Putin reacted to the killing during a televised appearance on Thursday even before the shooting was officially confirmed.

He called it "Ukraine's latest political assassination" and accused the Ukrainian government of doing nothing to investigate the deaths.

Putin had himself branded the killing of Russian opposition activist Boris Nemtsov in Moscow in February as a "provocation".

Ukrainian interior ministry official Anton Gerashchenko said he suspected Russia of ordering the killings to sow "terror" and make it look like Ukraine's government was hunting down its rivals.

Ukraine and the West accuse Russia of arming the rebels who have gained control of much of eastern Ukraine, a charge Russia denies.

 

- Finger pointed at Russia -

 

Buzyna was editor of the daily newspaper Segodnya, financed by Rinat Akhmetov, Ukraine's richest man and a leading sponsor of Yanukovych's Party of Regions.

The journalist also regularly appeared on Russian television commenting on the Ukraine crisis.

Son of a KGB officer, Buzyna wrote on his website calling for the federalisation of Ukraine as desired by its former Soviet master Russia.

The crisis has fuelled a surge in nationalism in both countries.

The OSCE European body monitoring a supposed ceasefire in eastern Ukraine condemned the killing and called on Ukrainian authorities to protect journalists.

Kalashnikov, 52, was accused of organising hired thugs in a crackdown on pro-European demonstrators last year during the uprising that led to Yanukovych's ousting -- dubbed the Maidan movement after the Kiev square where they rallied.

Interior ministry advisor Anton Gerashchenko said police had opened a murder investigation into Kalashnikov's killing which will examine his political activities as well as other possible motives.

"I do not exclude the possibility that these murders were organised by Russian special services to create an atmosphere of terror in Kiev, an atmosphere of hysteria, to show what happens to people who were against Maidan and against the new government," Gerashchenko said.

- Suspect suicides -

This week's deaths followed a spate of apparent suicides by allies of Yanukovych, some of whom faced allegations of orchestrating a violent crackdown on the Maidan protests.

Yanukovych's 33-year-old son Viktor Jr. also died in February at the wheel of a vehicle that apparently fell through ice on Russia's Lake Baikal.

Kiev had denied any link between the suicides, saying that in one case a former governor killed himself to avoid trial over the crackdown on protests.

Yanukovych fled to Russia in February 2014 and Ukraine descended into conflict. Russia annexed Crimea in March 2014 and fighting is rumbling on between pro-Moscow rebels and Ukrainian government forces in the east despite the February ceasefire.