ISLAMABAD (AP) -- Pakistan announced Tuesday that it has temporarily allowed NATO to ship perishable food to its troops in Afghanistan, a sign of thawing tensions following American airstrikes last year that accidentally killed 24 Pakistani soldiers.

Pakistan closed its Afghan border to NATO supplies in response to the deadly Nov. 26 attack on two of its border posts. The closure has been a headache for coalition forces, who have had to spend much more money to get goods to Afghanistan using alternative routes.

Pakistani Defense Minister Ahmed Mukhtar said the government would only allow NATO to ship perishable items for a limited time and has asked the coalition not to order any more. He did not indicate when the approval was given.

The U.S. and Pakistan still disagree over who should be blamed for the November attack, but there have been growing signs that relations are improving.

There was a temporary hiccup in that process Tuesday when Pakistani police briefly detained a U.S. Embassy employee after bullets were found in his luggage at an airport in the country‘s northwest. But the man was handed over to American officials after a couple hours.

The move to allow food items to enter Afghanistan could be a precursor to opening the border altogether.

Pakistan’s parliament is expected to vote on a revised framework for relations with the U.S. this week that could pave the way for the government to reopen the supply line.

Also, senior Pakistani officials have said in recent days that the government should fully reopen its border to NATO supplies as long as it can negotiate better fees from the coalition.

Pakistan security forces met with their NATO and Afghan counterparts Tuesday to discuss improving security for the upcoming coalition convoys, said spokesman for the paramilitary Frontier Corps Saeed Ahmed. They met in the city of Chaman in southwestern Baluchistan province, one of Pakistan‘s two Afghan border crossings.

For most of the 10-year war in Afghanistan, 90 percent of supplies shipped to coalition forces came through Pakistan, via the port of Karachi. But over the past three years, NATO has increased its road and rail shipments through an alternate route that runs through Russia and Central Asia. The northern route was longer and more expensive, but provided a hedge against the riskier Pakistan route.

Before the accidental American airstrikes on Nov. 26, about 30 percent of non-lethal supplies for U.S. and coalition troops in Afghanistan traveled through Pakistan.

The U.S. has since increased the amount of supplies running through the northern route, but this has cost it a lot more money. Pentagon figures provided to the AP in January showed that the alternative transport was costing about $104 million per month, $87 million more per month than when the cargo moved through Pakistan.

The U.S. Embassy employee detained at an airport in the city of Peshawar had 13 bullets in his luggage, said police officer Dost Mohammad Khan. It was unclear why the bullets were there. The man was scheduled to fly to Islamabad.

A U.S. official said the man was an embassy employee and had diplomatic immunity. He said the U.S. Embassy was in contact with the Pakistani authorities ``about the details of the case.’‘

The U.S. official spoke on condition of anonymity because he was not authorized by Washington to be named in the media.

There is a large U.S. consulate in Peshawar, which is close to the Afghan border.

The presence of American diplomats inside Pakistan emerged as a sensitive issue after a CIA contractor killed two Pakistani men in the eastern city of Lahore a year ago. U.S. officials insisted the shooter had diplomatic immunity, but Pakistan held him in jail for around two months, causing severe strain in U.S-Pakistan ties.

The unilateral American-raid that killed Osama bin Laden in a Pakistani army town in May last year also led to a fresh wave of suspicion against Western diplomats by the Pakistani security establishment, which was apparently stung by the realization that the CIA agents were operating in the country without its knowledge.