Ukraine says a Security Service (SBU) colonel was killed and three others injured when a car exploded in the Donetsk region on June 28.
The SBU said in a statement that Yuriy Vozny was killed when the car he was traveling in with three others exploded in the Kostyantynivka district of a Ukrainian-controlled portion of the Donetsk region.
Vozny's death came a day after Ukrainian Colonel Maksim Shapoval was killed by a car bomb in Kyiv.
The three people injured in the June 28 blast were hospitalized with varying injuries.
The SBU said that Vozny is the 23rd officer in the service to have been killed since fighting began in eastern Ukraine in 2014.
Meanwhile, the Ukrainian General Staff said on June 28 that its forces had killed two Russia-backed separatists in a clash in eastern Ukraine, including a Russian captain named Aleksandr Shcherbak.
The general staff said it had also captured a Russian citizen in the same incident.
The BBC's Russian Service identified the captive as Viktor Ageyev.
Russia denies it has active soldiers fighting in Ukraine.
More than 10,000 people have been killed in fighting in eastern Ukraine since early 2014.
With reporting by AFP and Interfax