Russian Foreign Minister Sergei Lavrov held calls on Saturday with his Turkish and Hungarian counterparts, the Russian foreign ministry said, hours after a summit between the U.S. and Russian presidents yielded no deal on ending the war in Ukraine.

The president of Ukraine and his European allies are to visit the White House on Monday, after President Trump backed Russia’s plan to end the war.

"This is a Russian tactic before any negotiations," Alina Alekseeva, the deputy head of Ukraine's Center for Countering Disinformation, told the Kyiv Independent.

The Ukrainian military said on Saturday that it had pushed Russian forces back by about 2 kilometres (1.2 miles) on part of the Sumy front in northern Ukraine. There was no immediate comment from Russia,