Two Russian soldiers captured while fighting in war-torn eastern Ukraine are being transported to the capital, Kiev, a Ukrainian military spokesman has said.

The Russians were wounded and taken prisoner near the frontline town of Shchastia in the Luhansk region on Sunday, Ukrainian officials reported.

Russia-backed separatists in eastern Ukraine have been fighting government troops for a year, and Moscow has vehemently denied it is supplying them either with weaponry or troops. When several Russian soldiers were captured on Ukrainian territory last summer, the Russian president, Vladimir Putin, said they had simply got lost.

Asked about the new reports on Monday, Putin’s spokesman again denied any Russian involvement. “We have said repeatedly that there are no Russian troops in Donbass,” Dmitry Peskov said, referring to eastern Ukraine.

The separatist mouthpiece Luhansk Information Center said on Sunday the men identified by Ukraine as Russian officers were in fact two policemen from Luhansk who had been taken prisoner near Shchastia.

Vladislav Seleznev, spokesman for the Ukrainian general staff, said on Monday the two men were being questioned by the Ukrainian security service and were on their way to Kiev where they would face the media.

Another Ukrainian military spokesman, Andriy Lysenko, told a televised briefing on Monday that the capture of the men would no longer allow Russia to deny its military presence in Ukraine. “They were there on a mission and they were killing our people,” he said.

The Ukrainian security service chief, Valentyn Nalyvaichenko, has hinted that Ukraine would not seek to exchange the men for any Ukrainians that the separatists or Russia may be holding. He was quoted on Sunday by the Interfax agency as saying that the men were facing criminal responsibility.

A video posted by a member of parliament on Sunday showed one man who said he was a Russian army sergeant.

The man shown lying in a hospital bed introduced himself as Sgt Alexander Alexandrov of the Russian special forces from the Volga river city of Togliatti. He said he was operating in the area in a group consisting of 14 men and had been based in the rebel stronghold Luhansk since 6 March. He and his comrades had been rotating in and out of the area around Shchastia every four to five days, he said.

More than 6,100 people have been killed in the conflict, which has left large parts of Ukraine’s industrial heartlands in ruins. A ceasefire brokered by Russia and western nations in February has made the fighting less intense and deadly but the skirmishes between the separatists and Ukrainian troops are still a daily occurrence.

Grigory Maksimets, a medic of the pro-Kiev volunteer Aidar battalion, said he attended to the men when they were delivered late on Saturday to his hospital in Shchastia, a town less than 12 miles north of Luhansk and home to a strategic power station.

One man had been wounded in the shoulder and the other in the leg, said Maksimets, who works in intensive care. The men were caught by Ukrainian troops while on a reconnaissance mission around the power station, he said.

The men introduced themselves as Russian soldiers and were worried that the battalion’s doctors wanted to take their organs for sale, he added. “They asked not to be sedated because they were afraid we would take their organs,” Maksimets said, adding that their Russian commanders had warned them about this.