Moscow has detained a citizen of Uzbekistan over the killing of a top Russian General.
The Kremlin says the man arrested confessed to planting the bomb that killed Lieutenant General Igor Kirillov, who was chief of Russia's Nuclear, Biological and Chemical Protection Troops, on Ukraine's orders.
Kirillov was killed outside his Moscow apartment building on Tuesday when a bomb hidden in an electric scooter went off, making him the most senior Russian military officer Ukraine has assassinated inside Russia.
Ukraine's SBU intelligence service took responsibility for the killing and accused Kirillov of being responsible for the use of chemical weapons against Ukrainian troops.
Russia's Investigative Committee released a statement on Wednesday saying the suspect had told them during questioning that he had come to Moscow where he placed an improvised explosive device on an electric scooter that he parked outside the entrance to the apartment block and remotely detonated.
The statement also said the unnamed suspect had been offered the equivalent of A$158,000 and residency in a European country for his role.
Other people are still reportedly being identified and Russian Foreign Ministry spokeswoman Maria Zakharova said everyone involved in the killing would be found and punished.
Russia's UN representative is expected to raise the assassination at a United Nations Security Council meeting at the end of this week.