Islamabad:  The United States and Pakistan will have to work harder to stop their alliance from souring after an air attack by US-led forces killed 11 Pakistani soldiers at a border post, analysts said on Thursday.

There have been sporadic breakdowns in co-ordination between forces on both sides of the Afghan border in the past, but Tuesday's attack by US-led coalition forces had by far the deadliest consequences and could affect future cooperation.

"They may try to do some damage control, but I think the troops on both sides may not trust each other and cooperate," said Rahimullah Yousufzai, a newspaper editor and expert on Afghan and tribal affairs.

Eleven Pakistani Frontier Corps (FC) soldiers, including a major, were killed in the air strike in the Mohmand tribal region, which abuts Afghanistan's Kunar province.

The attack came amidst growing frustration among Islamabad's western allies over efforts by the new government to negotiate pacts to end militant violence on its side of the border.

Nato says such deals lead to more violence in Afghanistan as they provide opportunity to militants to orchestrate and launch cross-border attacks from their sanctuaries on Pakistani soil.

Drone attacks

Critics say the attack will harden opposition to drone aircraft missile attacks inside Pakistani territory which have become a feature of US operations in the region.

"It will definitely have an impact on the relationship and cooperation," said Mahmood Shah, a former head of security for Pakistan's seven tribal regions on the Afghan border, known as Federally Administered Tribal Areas (FATA). Think-tanks in Washington have raised doubts about the resolve and questioned the loyalties of these troops, just as they often accuse members of Pakistani intelligence of playing a double game.

Soldiers on the front line bristle at suggestions Pakistan is tough fighting Al Qaida but soft when it comes to the Taliban. More than 1,000 soldiers have died fighting in FATA alone.

The militants have killed many more outside the tribal region in their asymmetrical war against the state.