Hillary Clinton to find Afghan supply routes as Pakistan ties sour

US Secretary of State Hillary Clinton will visit Tajikistan and Uzbekistan this weekend to bolster ties with two countries lying on an Afghan supply route that could help Washington reduce its dependency on Pakistan as ties sour with its main regional ally.

Clinton will meet Tajik President Imomali Rakhmon on Saturday and move on to Uzbekistan for high-level meetings before heading home on Sunday, the State Department said, as Clinton wrapped up a trip to Afghanistan and Pakistan.

The trip marks Clinton's second swing through Central Asia in less than 12 months, a reflection of Washington's increased focus on Afghanistan's northerly neighbours as it begins drawing down US troops from the 10-year Afghan conflict.

Both Tajikistan and Uzbekistan are part of what Washington  calls the Northern Distribution Network (NDN), an alternative supply line for US-led forces fighting the Taliban in Afghanistan that also stretches through Russia, Latvia, Georgia, Azerbaijan and Kazakhstan.

The United States is aiming to reduce the proportion of its surface cargo that it brings through Pakistan to only a quarter by increasing its supplies through the northern route; in July it was still well over half.

Washington's agreements with NDN nations describe supplies as "non-lethal". According to diplomats and local officials, those include food, water, construction materials and fuel.

The northern route is becoming an increasingly important option for the United States as it tries to increase pressure on Pakistan and convince it to tackle Afghan Taliban militants Washington says are based in Pakistan.

Clinton, during a visit to Islamabad on Friday, delivered a sharp warning to Pakistan's leaders that they must step up counter-terrorism cooperation and root out safe havens used by militants, the latest in a series of acrimonious exchanges between the two uneasy allies.

Uzbekistan in particular has drawn new US attention. US President Barack Obama last month phoned his Uzbek counterpart, President Islam Karimov, to discuss the possible expansion of the northern supply route, and Clinton met with the Uzbek foreign minister to discuss similar plans.

In Congress, changes in US law are pending that would allow more military aid to Uzbekistan, despite its poor human rights record. Capitol Hill aides said the changes were made partly at the urging of the Obama administration.

US military aid to Uzbekistan has been restricted since 2004 because of its record as one of the most repressive countries to emerge from the former Soviet Union.

US officials say they want to expand the Northern Distribution Network to enable more movement on the network in both directions, turning what had been primarily one-way traffic into Afghanistan into a two-way conduit as the US begins pulling out material.

(Reporting by Andrew Quinn; Editing by Robin Paxton and Myra MacDonald)