Ukraine's defence minister claims pro-Russian militants have taken two of its soldiers hostage in the separatist eastern region of Lugansk.

It comes as Kiev tries to regain control of a number of government buildings taken over by pro-Russian rebels.

Witnesses say a number of combat vehicles have been seen flying Russian flags in Slavyansk.

Donnacha O'Beacháin is a lecturer in International Relations with Dublin City University, he says there are echoes of what happened in Crimea - when Russia annexed the region - but it's even more dangerous;