Updated

NATO secretary-general Anders Fogh Rasmussen says the alliance has observed a Russian "incursion" into Ukraine, which Russia denies.

During a visit to Copenhagen on Friday, Fogh Rasmussen told reporters: "I can confirm that last night we saw an incursion (into) Ukraine." Rasmussen did not give details of the alleged incursion but said "what we have seen last night is the continuation of what we have seen for some time."

Andriy Lysenko, a spokesman for Ukraine's security council, said some Russian military vehicles had crossed the border into Ukraine. Two British journalists said they saw Russian armored personnel carriers cross the border.

Russia's Federal Security Service said Russian forces are patrolling the border area but denied that military vehicles had moved into Ukraine.