A Ukrainian lawmaker wounded in an explosion in Kiev that killed two people blamed Russia today for the blast while investigators said they were considering various motives for what they called an act of terrorism.

Ihor Mosiychuk, a member of the populist opposition Radical Party, was hospitalised but did not suffer life-threatening injuries, while his bodyguard and a passerby were killed. Two others were wounded.

Since fighting with pro-Russian separatists in eastern Ukraine broke out in 2014, the number of incidents involving explosives outside the conflict zone has increased.

There has been a spate of vehicle bombings over the past 18 months in Kiev, the capital, and elsewhere, but investigators have failed to find those responsible.

Ukraine's state security service (SBU) said that unknown perpetrators had rigged a motorcycle with explosives on Wednesday that detonated as the lawmaker left a TV station.

Radical party leader Oleg Lyashko said he had no doubt the incident was politically motivated, while Mosiychuk blamed Russia. "I believe that the initiators are in Moscow, the executors are in Kiev," Mosiychuk said on Facebook.

I believe that the initiators are in Moscow, the executors are in Kiev

Russian involvement is one of the possible motives being investigated, deputy Kiev prosecutor Pavlo Kononenko told journalists.

"Another explanation is Mosiychuk's political activity, his public position within our country," he said. "A third explanation is an attempt on Mosiychuk's life for personal reasons."

The Kremlin dismissed the accusations as a product of anti-Russian sentiment.

"Beyond all doubt, these are new signs of this anti-Russian campaign which has unfortunately swept across Ukraine and Kiev," Russian President Vladimir Putin's spokesman Dmitry Peskov said in a conference call with reporters.

Relations between Kiev and Moscow collapsed in 2014 after Russia seized Ukraine's Crimea peninsula and backed a pro-Russian separatist insurgency in eastern Ukrainian regions.

Radical Party lawmaker Evhen Deidei posted photos on his Facebook page from the scene of Wednesday's attack which showed the burnt-out shell of a motorcycle in front of a damaged vehicle.

"Judging by the damage to the car and the shrapnel holes in the doors, the power of the explosion was pretty strong," he said. "There is a lot of blood on the stairs, where Ihor was situated at the time of the explosion."

The interior ministry's Shkiryak said political analyst Vitaliy Bala was one of the three wounded in the blast.

In June, a colonel in Ukraine's military intelligence was killed by a car bomb in central Kiev. In 2016 a prominent investigative journalist, Pavel Sheremet, was killed by an explosive device in his car.