Turkey has issued a security alert for prisons nationwide with members of the banned Kurdish Workers' Party (PKK) detained after 18 PKK militants broke out of a prison on Wednesday, an official statement said Friday.

The statement, issued by the Ministry of Justice's General Directorate of Penalty and Prisons, underlined that the authorities should take additional security steps in prisons to prevent further jailbreak.

"The wing, yard, kitchen, stairwell and areas beneath wardrobes and beds, as well as places where the prisoners spend most of their time, should be carefully examined," read the statement, adding that any spot that a tunnel could run beneath should be carefully examined as well.

On Wednesday, 18 PKK inmates broke out of the prison through a tunnel they dug in the eastern Turkish province of Bingol.

Seventeen of them have been caught en route to a PKK shelter and one remains on the run. About 2,000 Turkish gendarme forces have participated in the operation to recapture the escapees.

The PKK, listed as a terrorist organization by Turkey and part of the international community, took up arms in 1984 in an attempt to create an ethnic homeland in southeastern Turkey. Since then, over 40,000 people have been killed in conflicts involving the group.