Eight Ukrainian troops have been killed and 16 wounded in the war-torn east as pro-Russian rebels launched one of their fiercest attacks since the signing of a shaky ceasefire deal, Kiev security officials said on Wednesday.

"Over the past day there was one of the most intense bombardments of Ukrainian territory since the signing of the Minsk agreement," Ukraine's Security Council said in a statement, referring to the February peace deal. "Eight Ukrainian soldiers were killed and 16 were wounded", the statement said.