DONETSK, June 1 – Russian politicians are financing the separatist government in Donetsk to pursue anti-West geo-political interests, Alexander Borodai, the self-appointed prime minister of the breakaway region, said Sunday.

Borodai, a Muscovite and a Russian citizen, emerged as the leader of the ‘Donetsk People’s Republic’ in May as Ukrainian forces had stepped up their offensive against the rebels.

"Some Moscow politicians finance their own people in our government,” Borodai told Reuters. “That is an inevitable necessity," he said, without giving details.

This is the first time that a separatist leader has openly admitted the financial connection between Moscow politicians and the separatist fighters in Ukraine.

Russia’s political landscape is effectively controlled by the Kremlin. Borodai’s comment underscores the increasing role that Moscow has been playing in eastern regions of Ukraine to foment the separatism movement.

Ukraine, as well as the US and the European Union, have long alleged that Moscow has been working to destabilize and undermine Ukraine through sending weapons and fighters. Moscow has denied the allegations.

Borodai said Moscow is supporting the separatist regions in Ukraine because it would de-facto benefit from creation of a ‘buffer’ zone between the West and Russia proper.

"I think Russia uses us to pursue its geo-political interests, have a buffer between itself and the West. We do not deceive ourselves about that. But even knowing this, we stick to Russia because it is our culture," Borodai said.

The U.S. State Department said on Thursday that Secretary of State John Kerry had pressed Russian Foreign Minister Sergei Lavrov to end all Russian support for separatists and call on them to lay down their arms.

Czech Foreign Minister Lubomir Zaoralek said Russia was clearly behind the violent unrest, though there were no immediately effective steps the West could take to stop it.

Meanwhile, the pro-Russian rebels have now taken positions deeper into Donetsk, an industrial hub, setting up barricades and posts in residential areas in the hope that Ukraine's army would not fight in a densely populated area and endanger the urban infrastructure.

"We have no other option," Alexander Khodakovskiy, a defector from the Ukrainian state security service who now commands Battalion Vostok, the main rebel fighting force. "They should understand the consequences of fighting within a city if [President-elect Petro] Poroshenko wants to go down in history as 'The Bloody One'."

Battalion Vostok, which includes many fighters from Russia and other Russia-allied regions of the former Soviet Union, suffered major casualties around the Donetsk airport during the offensive by the Ukrainian forces on May 26-27.

The casualties included natives of Chechnya, a region of Russia where Moscow fought two separatist wars and which is now run by a Kremlin appointee Ramzan Kadyrov, who runs his own militia, or "Kadyrovtsy.”

"There are no Chechens now. There were. They left yesterday (on Thursday) with their injured and killed. There was only one casualty among the Chechens," Khodakovsky said. "They were volunteers, not Kadyrovtsy."

Echoing Moscow's denials of involvement, Kadyrov says he has not sent his men to fight in eastern Ukraine but that some have apparently gone of their own accord.

Denis Pushilin, another separatist leader in Donetsk, said after the battle for the airport, which is now controlled by the Ukrainian army, that the bodies of "volunteers" from Russia would be returned home, openly acknowledging involvement from across the border. (nr/rt/ez)