COPENHAGEN NATO's Secretary-General Jens Stoltenberg urged Austria and Turkey on Friday to resolve a diplomatic dispute that has led to some cooperation programmes being blocked.
Turkey, a NATO ally, has withdrawn from some alliance participation - mostly military training - saying the move is aimed only at Austria.
"It is a very unfortunate situation and it means some cooperation programmes can't be launched," Stoltenberg told reporters during a visit to the Danish capital Copenhagen.
Austria, which is not a NATO member but cooperates with the alliance, led calls last year to halt Turkey's European Union accession talks. Vienna has also spoken out against Turkish politicians holding rallies in European countries.
"It's a bilateral situation between Turkey and Austria and we strongly urge them to solve it, so that it won't have negative consequences for the cooperation," he said.
The diplomatic tensions predate a current escalation with other European countries like Germany and Netherlands but as fellow NATO members Turkey cannot block cooperation with them.
Turkish President Tayyip Erdogan has compared Germany and the Netherlands to fascists and Nazis for stopping Turkish politicians from rallying to promote a referendum granting him sweeping new powers.
Erdogan on Thursday said Dutch Prime Minister Mark Rutte had lost the friendship of Ankara after the diplomatic row.
NATO officials told Reuters that the blocking also affected other countries that cooperate with the alliance but are not members.
Separately, Austrian tabloid newspaper Oesterreich said its website was brought down on Friday morning by a cyber attack "from Turkey", the latest in a series of similar incidents that appear to be connected to Vienna's spat with Ankara.
It did not present evidence to support the accusation.
"The Turkish cyber attack on our website was launched out of anger by Erdogan's cadres because oe24 and Oesterreich report critically and independently on Erdogan and his policies," the newspaper said in an article.
(Reporting by Teis Jensen in Copenhagen, additional reporting by François Murphy in Vienna writing by Nikolaj Skydsgaard and Stine Jacobsen; Editing by Gareth Jones and Julia Glover)