NATO forces will begin their offensive on the Taliban stronghold of Kandahar in June, a US official told AFP late Monday.
The offensive "has already begun but clearing operations will begin (in June)," the official said on condition of anonymity.
NATO and US forces had already announced plans to begin Kandahar operations this summer, but without giving specific dates.
Coalition forces have already launched a major offensive against the Taliban in Helmand province, near Kandahar, in an attempt to regain ground against the fierce insurgency.
The United States and NATO are boosting their military effort to 150,000 troops in Afghanistan in coming months as efforts to eradicate the Taliban threat intensify, with concentration on the militants' southern strongholds.
US General Stanley McChrystal said earlier this month he would take on Taliban militants in their Kandahar strongholds this summer when enough reinforcements are on the ground.
McChrystal, the US war commander, told President Barack Obama by video conference at a war cabinet meeting that the military was on course to pour thousands of extra troops into Afghanistan in the coming months, while he reported "continued progress" in the offensive against the Taliban in Marjah.
A US combat brigade of 4,000 men was already deployed in Kandahar in the summer of 2009 to secure lines of communication leading to the capital of southern Afghanistan, historic stronghold of the Taliban movement.