US negotiators are leaving Pakistan with no agreement on a supply route to NATO troops in Afghanistan have been reached.

­Part of the US team left Islamabad over the weekend and the rest will leave shortly. However, they will be prepared to return on short notice if circumstances change, Pentagon spokesman George Little said on Monday.

"We will continue to work through the (ground supply route) matter with Pakistan. And the members of the team that are leaving, or have, left are prepared to return to Islamabad at any moment to continue discussions in person," Little said.

Senior Pentagon official, Peter Lavoy, held talks with senior Pakistani officials over the weekend, but he failed to meet with Gen. Ashfaq Parvez Kayani, chief of the Pakistani army, Pentagon said.