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.

Deaths have been reported on either side of the border, just hours after a third round of ceasefire talks took place in Turkey.

Donald Trump has given Russia a shorter window of 10 to 12 days to agree a ceasefire in Ukraine or face tighter sanctions, as his frustration with his Russian counterpart escalates.