Kabul, Afghanistan (CNN) -- The head of a Kandahar prison where a mass escape occurred this week was among 20 people arrested Thursday on suspicion of assisting the jailbreak, a senior prison official told CNN.
Suspicions have run high that -- given the ease and scale of the escape -- there was some inside help at the prison. Guards as well as officials on duty during the night of the escape were arrested.
"The escape of the prisoners are not possible without authorities' cooperation," said Gen. Amir Mohammad Jamshid, the chief director of jails in Afghanistan.
Ghulam Dastagher Mayar, the chief director of the Kandahar jail, is among the arrested officials.
Monday's break was the second escape at the prison in three years. In 2008, as many as 1,000 prisoners -- nearly half of them Taliban members -- escaped after militants detonated a truck bomb against the side of the prison compound.
Afghan authorities said Tuesday they have recaptured 65 of the more than several hundred inmates who slipped out of the prison through a nearly quarter-mile tunnel dug beneath the compound.
A massive search operation continues to find the others -- many of them insurgent fighters, said the Kandahar governor's office.
The Taliban issued a statement taking responsibility for the escape from the prison in Kandahar, the Taliban's birthplace. Taliban spokesman Zabiullah Mujahed said digging the tunnel took five months. The escape took four and a half hours, he said.
The Taliban claimed 541 prisoners escaped. The NATO-led International Security Assistance Force said the number of escaped prisoners was closer to 470. The Taliban said 106 of the escapees were military commanders, but there was no immediate government confirmation of the claim.
The prison houses some of the country's most dangerous Taliban prisoners, and the escape was an embarrassment for the Afghanistan government and its Western allies, said CNN National Security Analyst Peter Bergen.