KIEV, May 23 – Russia should stop massive supplies of lethal weapons to separatist enclaves and withdraw its troops immediately from Ukraine, President Petro Poroshenko told President Putin in a phone call early Tuesday.

Poroshenko, Putin and leaders of France and Germany have spoken by telephone as fighting has escalated in parts of Donbas controlled by pro-Russian separatists.

“Russia must withdraw its troops from the occupied parts of Ukraine and stop supplying weapons and mercenaries,” Poroshenko said, according to his press service.

Russia keeps about 7,000 of its troops in parts of Donetsk and Luhansk reinforcing a 25,000-strong army of the separatist enclaves that mostly consists of Russian mercenaries, according to Ukrainian military intelligence.

Russia recently increased supplies of lethal weapons and ammunitions by railroad to the key separatist strongholds of Debaltseve and Ilovaysk, the intelligence agency reported.

Russia persistently denies presence of its troops in Ukraine, and says it only supplies humanitarian aid to the enclaves.

In the phone call, which was joined by French President Francois Hollande and German Chancellor Angela Merkel, Putin accused Ukraine of shelling the enclaves, a charge that has not been supported by international observers.

"Putin called for an immediate end to attacks by Ukrainian armed groups on settlements in Donbas,” the Kremlin said in a statement following the call.

Putin has been persistently trying to engage Ukraine in negotiations with Moscow-controlled separatist leaders of Donetsk and Luhansk to force Kiev into a federation state whose foreign policy would largely be decided by Donetsk and Luhansk.

Ukraine said any political discussions with Donetsk and Luhansk must come after Russia withdraws its troops allowing Ukrainian guards to control the border.

The commander of U.S. troops in Europe said earlier this year that “Russia will dial up and down the pressure along the line of contact to keep Kiev under pressure to meet their parts of the (Minsk) agreements first."

At a recent meeting with G7 ambassadors, Poroshenko said it was important to deploy an armed OSCE police mission in Donbas, which is critically needed to settle the crisis in a political way.

"We can talk about political leverage only after there are security-related prerequisites, progress in the deployment of the armed OSCE police mission, a sustainable ceasefire, the withdrawal of artillery systems and heavy equipment, the removal of Russia's occupying troops, the release of hostages," Poroshenko said. (nr/ez)