Afghanistan's interior ministry is investigating video footage that appears to show several men in police uniforms and other men with guns torturing an alleged suicide bomber.
The footage shows the armed men tying the man to the back of a police truck and dragging him along a main road in the south of the country.
One man in police uniform is then seen biting the man's arm while others kick and punch him.
The video went viral on social media on Tuesday.
The ministry said those involved have not been identified.
"Several men whose identities are not yet known, are torturing an alleged suicide bomber in Panjwai district of Kandahar province," the government said in a statement on Wednesday.
Kandahar is the birthplace of the Taliban, insurgents whose five years in power was ended by a US-led coalition and Afghan fighters in late 2001 in the wake of the September 11 attacks on the United States.
Despite some progress, torture and ill-treatment of detainees remains rife in Afghan prisons.
A UN report released on February last year, showed a 14 per cent decrease in the number of detainees tortured or ill-treated in Afghanistan.
A third of all prisoners were found to have been tortured.
