One civilian bus was struck a roadside mine planted by militants Tuesday morning in southern Afghan province of Kandahar, leaving at least 12 people dead and 15 others were injured, all civilians, said a statement issued by the provincial government.

"It occurred at around 09:00 a.m. local time this morning when a bus carrying civilians hit a mine as it passed through Maiwand district," the statement said.

It added that all the victims were innocent civilians and blamed "enemy of Afghanistan", a term for Taliban militants, for the bloody incident.

A fresh U.N. report has described 2009 as the deadliest year in terms of civilian casualties in Afghanistan ever since the commencement of U.S.-led war against Taliban and al-Qaida militants in the country.

Over 1,500 civilians have been killed in attacks by both the Taliban insurgents and the Afghan and the international forces up to the month of August, according to the report.