The ministry said the soldiers were killed during a clash with "terrorists" following "an attempted intrusion" of the base near Metina in northern Iraq.

The assailants were presumed to be members of the Kurdistan Workers' Party (PKK) which Ankara and its Western allies classify as a terrorist group, private Turkish channel NTV reported.

Turkish authorities announced a military operation was under way in the area in response.

Twelve Turkish soldiers were killed late last month in two separate attacks on Turkish military bases in northern Iraq.

The Turkish army regularly launches military ground and air operations against PKK fighters and their positions in northern Iraq, as well as autonomous Kurdistan or in the mountainous Iraqi region of Sinjar close to the Turkish border.

In the past 25 years Turkey has installed several dozen military bases in Iraqi Kurdistan to fight the group, which also has rear bases in the area.

The PKK, which has been involved in an armed struggle against Ankara since 1984, claimed responsibility last October for an attack on the headquarters of the Turkish interior ministry in Ankara which saw two police officers injured.