Ukraine's Poroshenko warns of Russian invasion threat after fighting surge

A Ukrainian serviceman jumps from an armoured personnel carrier (APC) in Avdeyevka near Donetsk, Ukraine, June 4, 2015. REUTERS/Oleksandr Klymenko

KIEV (Reuters) - Ukraine's president told his military on Thursday to prepare for a possible "full-scale invasion" by Russia all along their joint border, a day after the worst fighting with Russian-backed separatists in months.

His address in parliament was one of the first times Petro Poroshenko has used the word "invasion" to refer to Russia's behaviour since the start of a separatist rebellion in the east in which the United Nations says more than 6,400 people have been killed.