(CNN) -- Pakistan's prime minister assured the U.S. ambassador that any delays in trucks delivering supplies to NATO troops in Afghanistan are not caused by his government, his spokesman said Thursday.
Shipments along Pakistan highways began to roll last week for the first time in seven months after U.S. Secretary of State Hillary Clinton apologized for an incident in which coalition forces mistakenly killed 24 Pakistani troops.
A day after the apology, Islamabad decided to reopen the crucial supply routes shut down on November 27, 2011.
Because Afghanistan is landlocked, many supplies for NATO-led troops fighting Islamic militants have to be trucked in from Pakistan.
While a handful of trucks, under heavy security, crossed into Afghanistan from Chaman in Pakistan's Balochistan province last week, hundreds are still stuck inside Pakistan,
U.S. Ambassador to Pakistan Cameron Munter asked Prime Minister Raja Pervez Ashraf about the delays in a Wednesday meeting, said Akram Shaheedi, the prime minister's spokesman.
"The government has given all kind of clearances for the release of NATO supplies," Shaheedi said.
The only issues remaining are between the transporters and NATO, Shaheedi said.
The Pakistani routes are shorter and more direct route than the one NATO had been using since November that went through Russia and other nations, avoiding Pakistan altogether.
It has cost the United States $100 million more a month to use the alternative northern route.