Ukrainian President Petro Poroshenko sparked fresh Kremlin fury on Wednesday by warning that his crisis-torn country was fighting a "real war" against Russia.

Ukrainian President Petro Poroshenko sparked fresh Kremlin fury on Wednesday by warning that his crisis-torn country was fighting a "real war" against Russia.

The pro-Western leader said the weekend capture of two purported Russian special forces members proved the separatist uprising in the industrial east of Ukraine was a guise for a Moscow-orchestrated campaign aimed at breaking up his ex-Soviet state.

"This is not a fight with Russian-backed separatists, this is a real war with Russia," the 49-year-old Ukrainian leader told the BBC.

"The fact that we captured... Russian regular special forces soldiers (is) strong evidence of that."

Ukraine's military on Tuesday showed off two wounded Russians who had been taken prisoner during a firefight in Lugansk -- a blue-collar region that together with neighboring Donetsk revolted against Kiev's shift toward the West 13 months ago.

The men testified during a taped interrogation that they entered the war zone nearly two months ago as part of a 200-strong reconnaissance unit from the Russian army's Main Intelligence Directorate (GRU).

A Ukrainian Security Service spokesman said the suspects have been charged with involvement in "terrorist activity" and given a chance to phone their relatives back home.

Moscow acknowledges the presence of Russian "volunteers" and off-duty servicemen in Ukraine, but rejects charges they are there under orders from President Vladimir Putin's generals.

Putin's spokesman Dmitry Peskov said flatly that the "Kremlin does not agree" with what the Ukrainian leader told the BBC.

"First of all, one has to understand that unfortunately, Kiev is waging war against its own citizens," Russian news agencies quoted Peskov as saying.

"They are the ones coming under fire and they are the ones dying," said Peskov. "We should probably be talking about that first."