Russian MP Oksana Bobrovskaya and husband killed in car grenade blast

Police said they fear the husband may have detonated the grenade

Oksana Bobrovskaya was a member of Vladimir Putin's United Russia Party (Facebook)

A Russian MP and her husband, a former special services officer in the Russian military, were killed in an explosion in the back of her car on Thursday.

Witnesses say the bodies of Oksana Bobrovskaya and her husband Nikita were partially "naked below the belt" when they were removed from the rear of the vehicle.

Police said they fear her husband may have detonated the grenade.

"There is a version that he held in his hands a kind of grenade, or a piece of TNT," a police source said, according to The Siberian Times.

The couple were said to have "had a conflict" during which "the explosives detonated, their faces are disfigured," another Russian paper reported.

There were also claims a bomb was planted in the car, with the husband intended as the sole victim.

"We are checking all the versions, including this," a law enforcement source said.

Other police sources alleged the couple had rowed before the explosion, and Mr Bobrovskay had accused her of cheating with a "wealthy lover".

LifeNews claimed an anonymous police source said forensic evidence indicated Mr Bobrovskay may have forced his wife into a sex act before the incident.

The source reportedly said: "Presumably during a fierce conflict, he began to force her to perform her conjugal duty by threats and showing her an explosive device."

The couple had a four year old daughter.