Ukrainian President Petro Poroshenko has handed a letter to U.S. Vice President Mike Pence from relatives of Ukrainian hostages and received assurances of the U.S. assistance in their release.

"I handed Trump's vice president a letter from relatives of the hostages who are illegally held in prisons in the occupied territories [of Donetsk and Luhansk regions] and in the Russian Federation, and we received assurances that the U.S. administration will take efforts to help Ukrainians and in bringing our lads and girls home," Poroshenko told reporters in Washington on Tuesday, after the talks in the White House.