US Defense Secretary Jim Mattis met with top Afghan leaders during an unannounced visit to Kabul on Friday, adding his weight to a flurry of diplomatic efforts to bring the Taliban to the negotiating table.

His trip comes a little more than a year after President Donald Trump unveiled a revamped strategy for Afghanistan that saw him commit thousands of additional US forces to the war-torn country on an open-ended basis.

Mattis, on his fourth visit to Afghanistan since becoming defence chief in January 2017, has met with President Ashraf Ghani and the new US commander for American and NATO forces, General Scott Miller.