NATO's Secretary General has condemned moves by Russia to annex Ukraine's Crimea region.

Anders Rasmussen said Russia has disregarded all calls to step back into line with international law - and continues "down the dangerous path."

The Secretary General said there can be no justification to continue on this course of action, and he urged all sides to show restraint and take all possible steps to avoid further escalation.

Earlier Ukraine's military said an officer has been killed in an attack on a base in Crimea, the first such death since pro-Russia forces took control in February.

Ukraine has now authorised its troops to fire in self-defence.