Russian troops crossed border into Ukraine, Nato says

Nato has seen Russian military equipment and Russian combat troops entering Ukraine this week, its top commander Gen Philip Breedlove says, the BBC reports. 

Nato chief Jens Stoltenberg later urged Russia to pull back its forces.

Russia's defence ministry denied sending troops to eastern Ukraine to help pro-Russian separatists there.

The European OSCE monitoring mission has warned of "a real risk" of further escalation in a conflict that has killed more than 4,000 people.

Heavy artillery fire rocked the east Ukrainian city of Donetsk, the industrial hub held by pro-Russian separatist rebels, on Wednesday.

There were also reports of fighting near the rebel-held city of Luhansk, with one Ukrainian soldier killed and another injured, according to Ukrainian security forces.

BBC News