Ukrainian President Petro Poroshenko, right, gestures toward Russian President Vladimir Putin, left, as they meet with German Chancellor Angela Merkel, back to camera, and French President François Hollande, center, facing camera, in Milan. (Alexei Nikolsky/Associated Press)

A high-stakes meeting between the leaders of Ukraine and Russia ended Friday with little progress in resolving the conflict in eastern Ukraine, highlighting the increasingly intractable struggle there between government forces and Russian-backed rebels.

On a day when heavy fighting continued in the rebel-held city of Donetsk, Russian President Vladimir Putin and Ukrainian President Petro Poroshenko left meetings in Milan saying that they had made little headway in resolving Ukraine’s abundant problems.

A September cease-fire deal has been repeatedly violated. The specter of a natural gas shortage this winter looms over Ukraine. And Russia and the West remain embroiled in the worst tensions since the Cold War, with European leaders Friday offering gloomy assessments of the lack of progress in talks with Putin.

Putin, meanwhile, said that Russia is not involved in the conflict but that his government is ready to mediate to ensure that both rebels and Ukrainian forces pull back from current positions and live up to the cease-fire deal reached in September in Minsk, Belarus. Ukraine and its Western allies have said that Russia has fueled the seven-month conflict by sending troops and weaponry across the border, a charge the Kremlin denies.

“The parties firmly remain in support of the Minsk memorandum and are focusing their efforts on fulfilling all its provisions,” Poroshenko told journalists Friday.

Friday’s summit was only the third meeting between Putin and Poroshenko since the Ukrainian president’s election in May. The last meeting, in August in Belarus, took place shortly before columns of troops and tanks rolled into Ukraine from Russia, inflicting massive damage on Ukraine’s army and forcing Poroshenko to sue for peace.

In exchange for a cease-fire deal, the Ukrainian leader conceded broad rights of self-governance to areas of eastern Ukraine that are under rebel control. Similar pro-Russian separatist enclaves in Moldova and Georgia have allowed Russia to exert pressure on the governments of those former Soviet republics.

Putin said the first priority should be to solidify a line of separation between Ukrainian and
rebel-held territory to which both sides agreed in September. Those borders would essentially demarcate a new pro-Russian enclave inside Ukraine. Witnesses in recent days have said that Ukrainian border guards have started manning checkpoints in areas leading into rebel-held territory.

The line of separation “should be finished, and this is exactly what would help finally end the shelling and the deaths of peaceful, innocent people,” Putin told reporters in Milan after his meetings with Poroshenko. In his remarks, Putin repeatedly called the rebel-held territory Novorossiya, or New Russia, the rebels’ term for what they hope will be their new state. Putin’s use of the term was just the latest signal that Russia has little interest in helping Ukraine regain control of territory that until April formed the core of its industrial heartland.

Despite the cease-fire agreement, intense fighting has continued for control of Donetsk’s airport, which is the final outpost of Ukraine’s military near the rebel stronghold city. A Ukrainian military spokesman, Col. Andriy Lysenko, said Friday that three soldiers were killed in the previous 24 hours. Donetsk city administrators said explosions, shelling and shooting could be heard throughout the city center.

Fighting has also continued in other areas of eastern Ukraine, although the daily death toll has fallen markedly since its height in late August and early September.

Early Friday, a meeting between Putin and German Chancellor Angela Merkel — Europe’s most powerful interlocutor with Russia — ended in an impasse. Both sides used unusually blunt language to characterize the encounter.

Merkel and Putin “continued to express serious differences in views on the source of Ukraine’s domestic conflict, as well as the root causes for what is happening there today,” the Kremlin said in a statement.

“I cannot see any breakthrough so far,” Merkel said. “The key point is whether the territorial integrity of Ukraine is really being respected.”

In addition to the basic question of peace in eastern Ukraine, Russia and Ukraine are fighting over natural gas deliveries, which the Russian state-owned company Gazprom cut in June, citing nonpayment of debts.

Ukraine does not have enough stocks of natural gas to last it through the winter, meaning that it faces a shortage with potentially tough costs for its citizens. Natural gas is the primary fuel used for heating in Ukraine.

Poroshenko said the sides made little progress toward a deal, but he expressed hope that they could reach an agreement next week. Ukraine is holding parliamentary elections Oct. 26. Rebels plan to hold elections of their own Nov. 2.