<p><br /> Unknown attackers have targetted tankers carrying supplies for NATO troops in Pakistan.<br /> </p><p><br /> The attack came on the outskirts of the town of Shikarpur and is thought to be in retaliation for movements into the country by the international organisation.<br /> </p><p><br /> It comes a day after authorities blocked a supply route for troops, angered by the killing of three soldiers in airstrikes by NATO helicopters.<br /> </p><p><br /> A Paramilitary Rangers Force official said the attackers fired at the tankers before fleeing the scence. No one was injured.<br /> </p><p><br /> Pakistan is a crucial ally for the United States in its efforts to stabilise Afghanistan, but analysts say border incursions and disruptions in NATO supplies underline growing tensions in the relationship.<br /> </p><p><br /> The bulk of supplies for the troops in Afghanistan goes through Pakistan.<br /> </p>
