Police set up road blocks Thursday around a southern Afghan city in search of accomplices of a suspected Al Qaeda (search) bomber who killed 20 people in one of the worst terror attacks here since the ouster of the Taliban (search) in 2001, officials said.

The attacker detonated explosives strapped to his body during the funeral Wednesday in Kandahar city of a moderate Muslim cleric who had spoken out against Taliban-led insurgents. Among the dead was Kabul's police chief and six of his bodyguards. Some 42 people were wounded.

Security forces in Kandahar set up checkpoints on all roads out of the city and were checking vehicles for anyone suspected of having links to the bomber.

"We believe others were involved in the attack and we are trying to arrest them as soon as possible," said deputy police chief Gen. Salim Khan.

Parts of the bomber's body were found and Kandahar Gov. Gul Agha Sherzai (search) said he belonged to Usama bin Laden's (search) terrorist network. He said documents found on the body "show he was an Arab."

The attacker detonated the explosives after coming close to the police commander, a Karzai supporter, but it was not clear if he was targeted, said Interior Ministry spokesman Latfullah Mashal. Hundreds of others were in the mosque for the funeral of cleric Mullah Abdul Fayaz (search).

Fayaz, also a supporter of Karzai, was shot to death in Kandahar on Sunday by suspected Taliban gunmen — a week after he led a call for people not to support the rebels.

Kandahar was a stronghold of the Taliban regime that was ousted from power in late 2001 by U.S.-led forces for harboring bin Laden.

The bombing drew widespread condemnation, including from U.N. Secretary-General Kofi Annan who described it as a "heinous act of terrorism," U.N. associate spokesman Stephane Dujarric said in New York.

The blast — which came on the heels of a major upsurge in rebel violence in recent months including assassinations, almost daily clashes with rebels and the kidnapping of an Italian aid worker — further raised fears that militants here are copying the tactics of insurgents in Iraq.