U.S. Army Gen. Dan McNeill in Kabul (File Photo)

The top NATO commander in Afghanistan says hardfought gains by alliance troops this year could be lost, if Afghan security forces fail to hold ground seized from the Taleban.

In a British radio interview (BBC), U.S. General Dan McNeill said NATO forces have had success this year in driving Taleban fighters from the valleys of Afghanistan's southern Helmand province.

But McNeill says the Afghan national security forces have not been as successful in holding the captured territory. He says there is a chance the Taleban could return to the area in coming months, forcing NATO troops to do the clearing work again.

The NATO forces in the opium-producing southern province are mostly British troops. They say they have recaptured much of the Helmand River valley from the Taleban over the last six months.

Some information for this report was provided by AFP, AP and Reuters.