WASHINGTON: Afghanistan's Taliban insurgents use a sophisticated media strategy to portray themselves as stronger than they are and undermine confidence in the government, a leading think-tank says.

The administration and its backers must become better at countering this propaganda if they are to defeat an insurgency "that is driving a dangerous wedge between them and the Afghan people," the International Crisis Group says in a new report.

"The overriding strategic narrative is a quest for legitimacy and the projection of strength," it says.

"Out of power and lacking control over territory, the Taliban has proved adept at projecting itself as stronger than it is in terms of numbers and resources."