Skopje, Macedonia  - Neighbourly relations between Athens and Skopje were further soured Thursday when Macedonian President Branko Crvenkovski cancelled a trip to Athens in protest at a Greek ban on his flight.

"This action by Greek authorities contradicts international norms and principles and is not contributing to development of good neighbourly relations," Crvenkovski's cabinet said in a statement.

Crvenkovski was to take part in a biennial United Nations forum on natural resources in the region, but was informed by the Greek liaison office in Skopje that his plane would not be allowed to land.

The Greeks offered "alternate" transport, but Macedonia refused, the Makfax news agency said.

Greece and Macedonia have been embroiled in a diplomatic row over the name "Macedonia," which both claim as their own.

In April, Athens blocked NATO from inviting its northern neighbour to join because of the dispute, stirring strong anti-Greek sentiment in the former Yugoslav republic.

Greece does not allow Macedonian aircraft, including the carrier MAT, to fly over its territory and applied the same ban to Crvenkovski's official aeroplane. (dpa)