US President Barack Obama will meet Ukrainian President-elect Petro Poroshenko in Poland next week, a US official said on Friday.

The leaders will meet on Wednesday during Obama's upcoming trip to Europe, which will also include stops in Belgium and France, Deputy National Security Adviser Ben Rhodes told reporters in a telephone conference.

Obama will begin his four-day trip with a celebration in Warsaw to mark the 25th anniversary of Poland's first elections after communist rule. He will later meet leaders of G7 countries in Brussels before going to France for the 70th anniversary commemorations of the D-Day landings in Normandy.

US State Secretary John Kerry will accompany Obama during his visit to Poland and France, the State Department said in a statement on Friday.

At a regular press briefing on Friday, White House spokesman Jay Carney said Russian troops are withdrawing from the Ukraine border.

"There continue to be indications of activity on the border, including a number of units that appear to have withdrawn," Carney said. "We do not have confirmation that this represents a full withdrawal yet."

Over two-thirds of Russian troops have now pulled back from the border and several thousand troops still remain in the vicinity, State Department spokeswoman Jen Psaki told a press briefing on Friday.