US Defense Secretary Leon Panetta vowed Sunday not to let the United States be "gouged" by Pakistan on the price it charges for overland deliveries of American military supplies to Afghanistan.

Pakistan closed the land route to US supplies in November as punishment for a botched US air strike that mistakenly killed 24 Pakistani soldiers, but have been in negotiations to reopen the border crossing.

US defense officials have said the Pakistanis are demanding several thousand dollars for every truck crossing its border with the supplies, up from $250 per truck before the closure.

"We're not about to get gouged in the price. We want a fair price," Panetta said on ABC's "This Week."

Without the Pakistani supply lines, the United States has had to rely on a much longer, more expensive northern route to resupply its forces in Afghanistan.

The supply lines impasse is just one of a host of issues that have opened deep schisms in relations between the two countries, supposed allies in the US battle against Islamic extremists.

Relations plunged to an all-time low after a US raid by US special operations forces killed Al-Qaeda leader Osama bin Laden in a compound in a Pakistani garrison town on May 2, 2011.

The United States has moved gingerly to make up with the Pakistanis, who were incensed that they learned of the raid only after it had been carried out.

But the issue flared anew last week when a Pakistani court sentenced a doctor who helped the United States gather DNA data used to track down bin Laden to 33 years in prison for helping the Americans.

"It is so difficult to understand and it's so disturbing that they would sentence this doctor to 33 years for helping in the search for the most notorious terrorist in our times," Panetta said.

"What they have done here," he added, "does not help in the effort to try to reestablish a relationship between the United States and Pakistan."

The Senate Appropriations Committee has voted to cut US aid to Pakistan by a symbolic $33 million -- $1 million for each year of jail time given to Shakeel Afridi, the doctor.

The measure, an amendment to the $52 billion US foreign aid budget, passed in a 30-0 vote in a sign of growing frustration with Pakistan.

NATO air strike kills six children: Afghan officials
Kabul (AFP) May 27, 2012 - A NATO air strike killed a family of eight, including six children, when it hit their home in eastern Afghanistan, local officials said on Sunday.

President Hamid Karzai, who is a fierce critic of civilian deaths attributed to NATO forces, immediately ordered an investigation into Saturday night's incident in Paktia province, his office said in a statement.

"Eight people, a man, his wife and six of their children, are dead," local government spokesman Rohullah Samoon told AFP.

"It was an air strike conducted by NATO. This man had no connection to the Taliban or any other terrorist group."

A senior security official in Kabul confirmed the strike and deaths.

"It's true. A house was bombed by NATO. A man named Mohammad Sahfee, his wife and six of their innocent children were brutally killed," the official said.

A spokesman for NATO's International Security Assistance Force (ISAF), Lt-Col Jimmie Cummings, said it was investigating the claim.

Civilian casualties are a highly sensitive issue in Afghanistan and have often roiled relations between Karzai and the United States, which leads NATO forces in the fight against Taliban insurgents.

Karzai, who signed a long-term strategic pact with President Barack Obama this month, argues that civilian deaths caused by allied troops turn common Afghans against his Western-backed government.

He has also warned that such casualties threaten the pact with the US, with his office saying that "if the lives of Afghans are not protected, the strategic partnership will lose its meaning".

Karzai summoned ISAF commander General John Allen and US ambassador Ryan Crocker to the presidential palace just over two weeks ago after a number of civilians were killed in NATO air strikes.

NATO and US forces in Afghanistan admitted in a joint statement after the meeting that civilians had died in two separate hits.

The statement gave no details of how many civilians died in each of those incidents but local officials put the total at more than 20, including women and children.

"The president will be assured of our commitment to take any and all appropriate actions to minimise the likelihood of similar occurrences in the future," the statement said.

The number of civilians killed in Afghanistan's war has risen steadily each year for the past five years, reaching a record of 3,021 in 2011, the great majority caused by militants, according to UN statistics.

NATO has some 130,000 troops in Afghanistan, mostly from the United States, but they will withdraw by the end of 2014.

The latest civilian casualties come on top of a series of incidents this year that have rocked relations between the United States and its Afghan allies.

Videos and pictures have emerged of US forces abusing Taliban corpses, copies of the Koran were burnt on a major US military base and an American sergeant has been charged with 17 counts of murder over a massacre of civilians.