Daud Ahmadi, a provincial spokesman, said a suicide bomber on a motorcycle killed 12 Afghans, including two policemen, and wounded at least 23 people.
A statement released late Wednesday by NATO headquarters in Kabul said the explosion killed and injured dozens of Afghan civilians, Afghan national security forces, and coalition troops. The statement did not disclose further details about how many foreign troops had been killed or wounded.
"With today's horrendous attack at the Kajaki Sofla Bazaar, insurgents have once again destroyed the lives of dozens of innocent Afghan civilians," Allen said in the statement. "These attacks against the people of Afghanistan have no effect on the progress we are together making here with our Afghan partners and will only further isolate the Taliban from the process of peace negotiation."
Mullah Mohammed Omar, the Taliban's reclusive leader, "has lost all control over Taliban insurgents," Allen said, "otherwise he would immediately denounce these attacks and order his forces to stop attacking innocent Afghan civilians."
More than a year ago, Omar did urge his fighters to try to avoid killing civilians.
"Pay attention to the life and property of civilians so that . . . your jihad activities will not become a cause for destruction of property and loss of life of people," Omar said in a message e-mailed to the media in November 2010.
Suicide bombings and roadside bombs, however, have continued to kill ordinary citizens along with NATO and Afghan forces.