Kiev's Espreso television said Radical Party member Igor Mosiychuk was walking out of its studio after giving an interview Wednesday...
Kiev's Espreso television said Radical Party member Igor Mosiychuk was walking out of its studio after giving an interview Wednesday when an explosive device went off near a scooter parked on the street.
Mosiychuk's bodyguard died on the way to hospital and a passerby was killed at the scene.
Security Service of Ukraine spokeswoman Olena Gitlyanska told AFP a terror probe had been launched and that "the investigation is looking into all versions" of events.
But Deputy Prosecutor General Pavlo Kononenko told reporters that "the first possibility we are examining -- one Mosiychuk uttered himself -- is that this was organised by Russia's secret service".
Mosiychuk is a highly outspoken critic of the Kremlin and its alleged backing of an insurgency in eastern Ukraine that broke out two months after Kiev's February 2014 ouster of its Russian-backed regime.
Moscow denies playing any role in the conflict despite overwhelming evidence of its tanks and troops entering a war zone in which more than 10,000 people have died.
Kremlin spokesman Dmitry Peskov was equally dismissive of Ukraine's suspicion that Russia was behind the latest high-profile bombing to hit Kiev.
He told reporters that putting the responsibility on any Russian official demonstrated Kiev's "groundless hysteria" and "Russophobia".
But Radical Party leader Oleg Lyashko was adamant that "this is the work of our enemy's secret services".
The blast was the latest in a string of politically charged bombings to have hit the Ukrainian capital since last year.
Former Russian lawmaker Denis Voronenkov -- a Kremlin critic who had moved to Kiev -- was gunned down in broad daylight in the Ukrainian capital in March.
A car bomb killed journalist Pavlo Sheremet in July 2016. The independent Ukrainska Pravda news site's reporter had denounced the political courses taken by both Russia and Ukraine.
And a colonel with the Ukrainian defence ministry's intelligence service was killed when his car exploded in Kiev in June.
All three cases remain unsolved.
But Mosiychuk and the Radical Party play an ambiguous and relatively minor role in Ukrainian politics.
The small party stands in nominal opposition to the government but has also been willing to work with it in the past.
Mosiychuk himself spent 2011-2014 in jail after being convicted of involvement in an ultra-nationalist "terrorist" group.
The 45-year-old was further embroiled in a 2015 bribery case that was eventually dropped.