The White House on Monday sharply condemned a reported Taliban attack on a bus in southern Afghanistan, calling it evidence of the Islamists'' "outright war" on the people they once ruled.

Washington joins Kabul "in condemning in the strongest terms the October 16th massacre of more than 30 innocent civilians by Taliban extremists in Kandahar province," spokeswoman Dana Perino said in a statement.

"This barbaric attack is the latest disturbing chapter in the ongoing saga of the Taliban''s outright war on the people of Afghanistan," said Perino, who offered "heartfelt condolences" to the relatives of the victims.

Perino said the attack -- which came amid growing Afghan complaints over civilian deaths from US-led and NATO strikes -- highlighted "two competing visions for the future of Afghanistan."

"The United States -- along with our NATO partners -- train their soldiers, protect their civilians and help build their roads so that there might be a brighter day ahead for this struggling young democracy," she said.

"The Taliban and Al-Qaeda on the other hand, have stopped buses on those roads and brutally executed dozens of innocent civilians in order to stop that brighter day from ever coming," she said.