"There is no news from the hostages as of this morning... Let's see what impact the announcement of the transporters' union will have. Its decision is actually quite in line with the demands of the hostage-takers," the diplomat said on Tuesday, on condition of anonymity.

The International Transporters' Association (UND), which counts most of Turkey's 900 land transport companies among its members, said on Monday it was calling on its members to immediately stop transporting cargo to US troops in Iraq.

The announcement followed the release of an internet video apparently showing the shooting of a Turkish driver, identified as Murat Yuce, who was working for a Turkish company which provides services to the US army in Iraq.

Two Turkish truck drivers, Abd Al-Rahman Demir and Sait Unurlu, are currently being held in Iraq by the Tawhid wa al-Jihad group.

"Our efforts for their release are continuing. There are many undertakings which are not made public," said the diplomat, who noted that five Turks had been set free in June.

Whereabouts unknown

The official said there was still no information as to the whereabouts of a Turkish worker who was last seen together with Yuce several days ago.

"Our efforts for their release are continuing. There are many undertakings which are not made public"

Turkish diplomat

Also missing is a truck driver. His family fears he was seized after coming under attack on a road linking Baghdad and Tikrit last month.

Foreign Minister Abd Allah Gul has declined to say how many Turkish nationals are being held in Iraq.

The diplomat confirmed media reports that another driver, Ferit Nural from southern Turkey, was killed in an armed attack on a road near Baghdad on Monday.

The Turkish press on Tuesday expressed outrage at the murder of Yuce, who was apparently shot in the head.

The mass-circulation Hurriyet issued a statement saying: "The account will be settled one day," calling the perpetrators "masked cowards".