Two people, including a six-year-old Russian girl, were killed and 10 hospitalized in Tiraspol, when two grenades detonated on the trolleybus. Two unexploded grenades were subsequently discovered at the scene.
Vladimir Antyufeyev said explosives had been confiscated from the suspect, a resident of Tiraspol, which he had kept since the armed conflict between Transdnestr and Moldova in 1992.
Antyufeyev said the detainee had acted alone, was not connected with an organized group, and that the explosion had nothing to do with Moldovan special services. He declined to name the suspect or divulge his motives.
"I will not state the motives, in the interests of the investigation," the minister said.
Experts from Russia's Federal Security Service helped Transdnestrian law-enforcers to detain the suspect, he said.
The attack was the second fatal incident to strike public transport in the area in just over a month. On July 6, an explosion blew the roof off a mini-bus taxi in Tiraspol, killing seven and wounding 23.