A delayed shipment of Israel Aerospace Industries-made Heron unmanned air vehicles to Turkey has become the focus of an international dispute.

Turkey had invited the Israeli defence forces to participate in a joint military exercise this month, but cancelled the invitation at the last minute.

The incident drew praise from some quarters, including Syria and Hamas, who viewed Turkey's decision as a rebuke for Israeli hostilities against Muslims. But the action provoked mild rebuke from the US Department of State.

"We think it's inappropriate for any nation to be removed from an exercise like this at the last minute," says the department.

Turkish media quoted unmanned air force officials in Turkey, who blamed the incident on delayed shipment of Heron UAVs by Israel.

An Israeli source acknowledges that IAI missed a delivery deadline, but firmly denies the most recent Turkish reports linking the lack of UAVs to the cancelled exercise.

"This allegation is ridiculous. There was a delay, but it was caused by problems in Turkey. The UAVs are being supplied," the source says.

The Turkish ministry of defence signed a $190 million deal in May 2007 with the Israeli UAV Partnership (IUP), formed between IAI and Elbit Systems, to deliver 10 Heron systems by October 2009.

IUP acts as the major subcontractor to Tusas Aerospace Industry for the programme.

IAI manufactures the Heron UAVs while Elbit supplies the ground stations. The Turkish company is supplying the payloads.

The Heron is a medium-altitude, long-endurance UAV that can operate at a distance of more than 1,000km (540nm) and at altitudes above 25,000ft (7,630m) for more than 24h.

The Turkish ministry of defence decided to equip the Heron with the standard 100hp (75kW) Rotax gasoline engine.

Source: Flight International