Ukrainian security forces said Wednesday that they captured a Russian Army major who was allegedly delivering explosives to pro-Moscow rebels in the country. 

Moscow has maintained that it is not involved in the ongoing conflict in eastern Ukraine between forces loyal to Kiev and the self-declared separatist republics that favor Russia. Numerous Russians captured in the conflict zone have been described as “volunteers” by the Kremlin. However, both Kiev and its Western allies have accused Moscow of supporting the insurgents by sending heavy weapons and troops.

The National Security Service of Ukraine (SBU) said the soldier, who was captured over the weekend in the disputed Donetsk region, had been identified as Army Major Vladimir Starkov, who had gone missing while driving a truck full of explosives to a separatist outpost, Agence France-Presse reported.

“Starkov immediately confessed to being a Russian citizen and to being an enlisted soldiers of the Russian armed forces,” SBU head Vasyl Grytsak reportedly said.

Ukrainian news weekly Novoye Vremya, cited by Sky News, published a transcript of a conversation between two pro-Russia separatists after they learned about Starkov’s detention.

“How did he get lost?” one of the fighters from the purported radio intercept asks. “He had taken that route a hundred times already!”

Ukraine previously arrested two alleged Russian fighters in May -- Sgt. Yevgeny Yerofeyev and Capt. Alexander Alexandrov -- who identified themselves as active servicemen in Russia’s forces sent on a reconnaissance mission in the area. However, Moscow said that the two had left official service by the time they were arrested.

On Tuesday, Kiev denied that it was exchanging the two Russians for Ukrainian prisoners of war, refuting the reports in Russian media. "They exchanged a few people, among whom were both Ukrainian citizens and citizens of other countries who fought for Ukrainian side,” local newspaper had quoted an anonymous Russian official as saying. “I can only add that our guys were subjected to severe torture in captivity.” Alexandrov’s lawyer Konstantin Kravchuk also reportedly confirmed the exchange.