KIEV, April 16 - A Ukrainian journalist known for his pro-Russian views was shot dead on Thursday in Kiev, a day after the killing of a political supporter of ousted Moscow-backed President Viktor Yanukovych, driving up tension between Moscow and Kiev, Reuters reported.

Russian President Vladimir Putin said the murders were political while Ukrainian President Petro Poroshenko described them as deliberate acts which "play into the hands of our enemies" and ordered an immediate and transparent investigation.

The killing of Oles Buzyna, who expressed strong pro-Russian views in a daily newspaper, and of ex-parliamentary deputy Oleh Kalashnikov were the latest in a spate of mystery deaths among allies of Yanukovych, who fled to Moscow last year.

Ukrainian officials and political analysts suggested they were the work of Russian special forces assassins out to blacken the image of Kiev's pro-Western authorities.

Buzyna, 45, wrote pro-Russian opinion pieces for Ukraine's Sevodnya daily, owned by Ukraine's richest businessman Rinat Akhmetov. He ran in last year's parliamentary election on behalf of the Russian Bloc party, but was not elected.

He was shot by assailants from a car in the middle of the day as he came out of the block of apartments near Kiev city center where he lived.

"Today at 1320 hrs(6.20 a.m. EDT) ... two unidentifiable men in masks shot journalist Oles Buzyna," the interior ministry said in an online statement.

A video clip showed a man lying on his back, surrounded by police and first aid workers. There was a heavy blood stain on his upper body.

On Wednesday evening, Kalashnikov, 52, a former member of parliament for Yanukovych’s discredited Party of Regions, was shot dead inside a multi-storey block as he went up to his eighth-floor apartment.

An interior ministry adviser said both victims played a part in the "Anti-Maidan" movement, which opposed pro-Western protests that ousted Yanukovych in February 2014 and were witnesses in criminal cases relating to pro-Russian activists who attacked protesters on the Maidan in early 2014.

Two former parliamentary deputies belonging to the Party of Regions were found dead from apparently self-inflicted gunshot wounds in March. Another prominent party worker killed himself in February by throwing himself out of a window and a fourth party member was found hanged.

Interior ministry official Anton Gerashchenko, speaking on the TV channel 112, said he could not exclude that the killings were the work of Russian special forces and he warned that opponents of Kiev's pro-Western authorities "could become the victims of Russian intelligence services.” (rt/ez)