Ukraine says separatists step up attacks, Poroshenko warns of 'threat of war'

KIEV (Reuters) - Ukraine's leader warned on Tuesday that a war with pro-Russian separatists could still break out again as its military said the rebels had greatly stepped up attacks and widened the area of their operations despite a ceasefire.

A military spokesman said one Ukrainian serviceman had been killed -- the fourth fatality among the Ukrainian armed forces in four successive days -- and 14 others wounded in a surge in violence at flashpoints in Ukraine's east and south-east.