Russia and Ukraine discussed further prisoner swaps on Wednesday at a brief session of peace talks in Istanbul, but the sides remained far apart on ceasefire terms and a possible meeting of their leaders.

Ukraine and Russia attacked targets on each other's territory on Thursday after brief direct talks between the two sides failed to make any progress on steps to end nearly three-and-a-half years of war.

Negotiators for the warring sides in Istanbul appeared to make little progress on ceasefire terms or a possible summit between their presidents – with their meeting ending after less than an hour.