ANKARA, July 6 (RIA Novosti) - At least four people were killed and another nine were injured in a landmine explosion in southeast Turkey early on Monday, national media said.

The blast went off in the Turkish province of Sirnak when a truck carrying construction workers hit a landmine on a road near the border with Iraq.

The explosive device is believed to have been planted by Kurdistan Worker's Party (PKK) militants, the Hurriyet newspaper said.

A search for the militants responsible is underway.

The PKK, considered a terrorist organization by the EU and the U.S., has been fighting for an autonomous ethnic Kurd state in southeast Turkey for nearly 25 years. The conflict has so far claimed over 40,000 lives.