Turkey has said it will not give in to Iraqi militants who have threatened to kill three Turkish hostages if Turkish firms do not leave Iraq.
A videoed message was aired by al-Jazeera TV
Turkey had never accepted any demands from extremists in 20 years of fighting terrorists, the defence minister said.
Footage on Arabic TV showed the men held by militants loyal to an al-Qaeda leader, Abu Musab al-Zarqawi.
Zarqawi's group has previously said it was behind the beheading of an American and a South Korean kidnapped in Iraq.
Al-Jazeera satellite channel broadcast footage showing the Turks kneeling in front of two black-clad gunmen and holding up their Turkish passports.
On the wall behind the group was a black banner bearing the words "Tawhid and Jihad", the name of Zarqawi's organisation.
In an accompanying message, they demanded that Turkish firms withdraw from Iraq within 72 hours - a deadline that expires on Tuesday - or the men would be beheaded.
They also urged Turks to protest during the Nato summit in Istanbul, during which President George W Bush will be seeking help in stabilising Iraq.
Turkish Defence Minister Vecdi Gonul rejected the demands outright.
"Turkey has been fighting terrorist activity for more than 20 years...They ask many things, they demand many things. We never consider them with seriousness," he said.
A Turkish consular official in Baghdad, speaking on condition of anonymity, told the Associated Press that the three hostages had disappeared two days ago, but declined to give any further information.
Observers say the abductions are likely to fuel the already high anti-war sentiment in Turkey. The government opposed the war and its troops are not part of the US-led occupation force in Iraq
However, many Turkish contractors work as drivers and support staff for US forces there.
Zarqawi's movement has already claimed responsibility for the beheading of two other hostages captured in Iraq - American Nick Berg and South Korean Kim Sun-il.
Both beheadings were filmed and the footage posted on Islamist websites.