Pakistan said on Wednesday that it has given passage to the international forces to withdraw from Afghanistan by reopening ground supply routes to NATO forces.

The resumption provides a boost for US President Barack Obama, whose administration has been criticized for paying extra money for the closed supply convoy, and the reopening also helps the Pakistani government win back respect and support from domestic public, analysts said.

US Secretary of State Hillary Clinton, in a telephone call on Tuesday with Pakistani Foreign Minister Hina Rabbani Khar, apologized for a November NATO airstrike that killed 24 Pakistani soldiers and prompted an infuriated Islamabad to slam the supply routes closed.

"We are sorry for the losses suffered by the Pakistani military. We are committed to working closely with Pakistan and Afghanistan to prevent this from ever happening again," Clinton said.

"Hillary Clinton's apology won a major concession from Pakistan. Otherwise the political impasse would be unfavorable for Pakistan to normalize its anti-terrorism cooperation with the US," said Hu Shisheng, an expert in South Asian studies with the China Institutes of Contemporary International Relations.

A customs official at one of Pakistan's two main border crossings - Chaman in southwestern Baluchistan province - said he received orders from the government to begin allowing trucks to cross into Afghanistan at 2 pm local time. He spoke on condition of anonymity because he was not authorized to talk to the media.

Officials at the Torkham crossing in the Khyber tribal area were still waiting for word from the government, said customs officer Asfandyar Khan.

Pakistan's cabinet on Wednesday endorsed the decision to reopen the route, which was made by senior civilian and military officials.

NATO Secretary-General Anders Fogh Rasmussen on Tuesday welcomed Pakistan's decision, saying the resumption of transit arrangements for International Security Assistance Force supplies through Pakistan demonstrates strengthened cooperation between ISAF nations and Pakistan.

Analysts also warned that the US-Pakistan ties are still far from repaired, and the possibility of closing the supply lines again remains, as some major problems have still not been resolved.

Washington and Islamabad still have differing views on anti-terrorist operations, and "once another incident with casualties or serious sovereignty infringement is triggered by the NATO armed forces, the supply lines may be closed again", Hu said.

The deal, which came after several previous attempts at negotiation had failed amid a dispute over a US apology, opened the prospect of broader improvement in US-Pakistan ties.

But even with this hurdle down, others remain. They include Pakistan's opposition to US drone strikes on its territory, and Washington's allegations that Islamabad condones, or even assists, anti-American militants.

Meanwhile, anti-US sentiment in Pakistan is rising, which may also add to the ups and downs between the two countries, Hu added.

The most vocal opposition to reopening the NATO supply line has come from a collection of hard-line Islamist religious leaders and politicians known as the Difah-e-Pakistan, or Defense of Pakistan Council.

"It is an insult to our nation," said chairman Maulana Samiul Haq. "The rulers have put national interest at stake just to please America."

The Pakistani Taliban vowed on Tuesday to attack trucks carrying NATO supplies once they started carrying supplies into Afghanistan, where most NATO soldiers are due to withdraw by the end of 2014.

Zhang Yunbi, AP, Xinhua and Reuters contributed to the story.