The Spanish troops died along with 13 crew when a Ukrainian Yak-42 plane flying them back from peacekeeping duties in Afghanistan crashed into a mountainside in northeastern Turkey as it attempted to land to refuel.

The crash has sparked angry claims that the plane was unsafe, with questions being asked about the roles played by the Ukrainian operator, the Spanish government and NATO's in-house transport agency Namsa.

"I don't think that it helps anybody to start pointing fingers of blame at the moment, when what was being used was one of the workhorses of that part of the world," Robertson told reporters in the southern Spanish city of Rota before heading to Madrid.

He stressed that Yak-42 aircraft were widely used across the region, including in Afghanistan where the Spanish troops had been deployed.

Spanish Defence Minister Federico Trillo, who has been fighting off claims from the victims' families that the Ukrainian aircraft was unsafe to fly, had defended the use of the plane by pointing out that it was covered by Namsa.

But the Spanish press later quoted NATO spokesman Yves Brodeur as saying that Namsa had no safety role and did not inspect planes.

"If the plane was not in a fit state to fly, the Ukrainian authorities should not have renewed its certification," he was quoted as saying.

Trillo later complained to the NATO secretary general over the spokesman's comments, but Robertson stressed on Thursday that NATO had not sought to contradict the Spanish minister.

He added that the Namsa agency "does its job... correctly and efficiently".

Trillo said on Thursday that it was "premature and irresponsible" to blame the crash on the plane's condition.

"I wish I could give a more satisfactory explanation to the (victims') families but I must insist on the fact that the plane was in good condition," he said in an interview with Cadena Ser radio.

The crash of the Yak-42, owned by Ukrainian charter company Sredizemnomorskiye, was the third accident involving Ukrainian planes in less than six months. The others occurred over the Democratic Republic of Congo and in Iran.

WAR.WIRE