KIEV, Oct. 14 - German Chancellor Angela Merkel and Ukrainian President Petro Poroshenko agreed more talks were needed before a "Normandy format" summit on the Ukraine conflict could be held, the German government said, Reuters reported.

The Kremlin had said on Thursday the leaders of France, Germany, Russia and Ukraine might meet on Oct. 19 if preliminary conferences of experts produced results.

Merkel and Poroshenko spoke by telephone on Thursday and agreed that everything should be done to stabilize the ceasefire agreed 18 months ago in Minsk and to implement other steps outlined in the agreement, the German government said. Russia and Ukraine each accuse the other of violating the ceasefire.

"There was also discussion about which preconditions were needed to allow a meeting for the leaders and heads of government in the so-called Normandy format," it said. "They agreed further discussions were needed before any such meeting."

In an opinion piece in the newspaper Frankfurter Allgemeine Zeitung on Friday Poroshenko said Russia is building up its military in eastern Ukraine, and he urged the European Union to keep sanctions against Russia in place.

"According to Ukrainian intelligence sources, there are more than 700 Russian tanks, more than 1,250 artillery systems, more than 1,000 personnel carriers and more than 300 rocket launchers in Donbas," Poroshenko wrote. "The pro-Russian fighters in Donbas literally have more tanks and rocket launchers than the German military."

Poroshenko said 19 Ukrainian soldiers had been injured in fighting along the line of conflict in eastern Ukraine since a Sept. 1 "back to school" ceasefire, with more than 800 shots fired by pro-Russian rebels in September and 500 in October.

"The war continues to rage and there are many signs that the Minsk process is stumbling over Russia's perpetual masquerade," he write. "It is time to correct our thinking about Russia's ambitions because they not only are a threat to Ukraine, but for security and stability in Europe."

He said Russia continued to deny supplying military equipment to separatists in eastern Ukraine, much as it had done in Crimea, which it annexed in 2014.

Ukraine's military on Sunday postponed a planned parallel withdrawal with pro-Russian separatists from Stanytsa Luhanska, a town on the eastern frontline, saying the rebels had disregarded the agreement and fired artillery at Ukrainian positions. (rt/ez)