|The deaths of 24 Pakistani soldiers in a NATO strike in November prompted widespread protests [AFP]
Islamabad has rejected a request by Marc Grossman, the US special representative to Pakistan and Afghanistan, to visit the country, a senior official told the Reuters news agency.
"Ambassador Grossman asked to visit Pakistan but we conveyed to him that it was not possible at the moment," a senior Pakistani government official, who declined to be named, said on Wednesday.
Relations between Islamabad and Washington are at the lowest point in years after 24 Pakistani soldiers were killed on November 26 in a NATO air strike in the region bordering Afghanistan.
The growing tension threatens to set back peace efforts in neighbouring Afghanistan, from where the US and NATO plan to gradually withdraw troops after a decade of war.
President Barack Obama’s special envoy will also visit Afghanistan and Qatar as part of the US strategy to involve the Taliban in talks for a durable peace, as the international forces led by the US are likely to pull out of Afghanistan by 2014.
Pakistan's co-operation is regarded as crucial because of its long history of association with armed groups.
Pakistan said in early December it had decided to review co-operation with the US and NATO. The review is currently before parliament with no firm timeline on when recommendations will be presented to the government.
Mark Toner, a US State Department spokesman, said on Tuesday that Pakistan had decided the review should be completed before Grossman's next visit.
Pakistan has accused the US of undermining its sovereignty, with the controversial unmanned drone attacks in the country's tribal regions being the bone of contention between the two countries.
There were also country-wide protests after a CIA contractor killed two Pakistanis in January last year in city of Lahore.
Relations between the two reached another low, when US special forces soldiers raided a compound not far from Pakistani capital, Islamabad, and killed al-Qaeda leader Osama bin Laden in May last year.