Turkey's truckers association said Monday it would stop delivering goods to U.S. forces in Iraq, in what appeared to be a direct response to insurgents' brutal, videotaped killing of a Turkish hostage and an attempt to win freedom for two other captives.

A video posted Monday on the Internet showed militants pumping three bullets into the head of a Turkish hostage, identified as Murat Yuce, who was kidnapped in Iraq. It was not clear when the shooting took place. Before he was killed, the man said he worked for the Turkish company Bilintur (search).

In Ankara, Bilintur told The Associated Press that the catering firm has an employee named Murat Yuce in Iraq, but had no knowledge that he had been killed.

Cahit Soysal, head of the International Transportation Association, said that Turkish truckers hoped that kidnappers would release the two other recently captured Turkish as a result of the organization's decision to stop deliveries.

Soysal said that 200-300 Turkish trucks bring supplies to U.S. forces in Iraq every day.

The Tawhid and Jihad (search) group of Jordanian militant Abu Musab al-Zarqawi (search) said in a video aired Saturday on Al-Jazeera television that it had kidnapped the two Turks and threatened to behead them within 48 hours. The Turks were identified as Abdulrahman Demir and Sait Unurlu.

The militants demanded that the Turk's employers leave Iraq. It showed three masked, black-garbed gunmen standing behind two seated men holding various forms of identification, including what appeared to be Turkish passports.

Earlier Monday, the Turkish trucking company for which the two drivers worked said it was unilaterally halting business in Iraq.

"We have halted all transportation to Iraq," company chief Omer Ozturk said. "We are now waiting anxiously for our drivers to be released."

Militants loyal to al-Zarqawi have claimed responsibility for a number of bloody attacks and beheadings of previous foreign hostages, including U.S. businessman Nicholas Berg (search), South Korean translator Kim Sun-il (search) and Bulgarian truck driver Georgi Lazov.