Kurdish rebels have killed 26 Turkish soldiers and wounded 16 others near Turkey's border with Iraq, in the deadliest such attack in years.

Turkish authorities say rebels from the Kurdistan Workers Party opened fire on military outposts in Cukurca and Yuksekova, in southeastern Turkey's Hakkari province.

Media reports say Turkish military forces responded by crossing into Iraq to pursue Kurdish rebels. Turkish warplanes were also reported to have carried out retaliatory air strikes.

Turkish President Abdullah Gul told reporters that “vengeance for these attacks will be great.”

The PKK has escalated attacks against Turkish targets in recent weeks. Turkish forces have responded by increasing the number of airstrikes against suspected rebel bases in northern Iraq. In August, Turkey's military said it killed as many as 160 Kurdish rebels in air and artillery strikes across the border.

Kurdish rebels have waged a campaign for autonomy in Turkey's largely Kurdish southeast since 1984. The conflict has killed more than 40,000 people.

The PKK is considered a terrorist group by Turkey, the United States and European Union.