KABUL - Thirteen prisoners, including some Taliban militants, escaped overnight from the main prison in the city of Farah, western Afghanistan, the police said Saturday.

The inmates used a tunnel to escape from the jail, which holds about 80 prisoners, Farah provincial police chief Faqir Ahmad Askar said.

"Among the escapees were political and criminal prisoners. A number of them were to be transferred to Kabul for their final court trial," he said.

"We have arrested one of the escapees. An investigation is under way to find out how they managed to escape and if they had any accomplice working in the prison."

Up to 1,000 Taliban inmates escaped from Sarpoza prison in Kandahar city in June after a suicide attack blew open the front gates and destroyed the walls.

The United States and NATO have more than 100,000 soldiers fighting alongside Afghan government forces to eradicate the Taliban insurgency, which has become more virulent in recent months.