Army spokesman Maj Gen Shaukat Sultan on Saturday said authorities agreed to a week long extension after local tribal elders in South Waziristan approached the government, seeking more time to convince foreigners to lay down arms and register themselves with the authorities.
"The extension is part of a political process, and we want to resolve the issue through talks," Sultan said.
A week ago, Pakistan set 30 April as a deadline, saying that if 'foreign fighters' promised to live peacefully, they would be allowed to stay in South Waziristan - the scene of a "counterterrorism" operation in April which left 120 people dead including 48 soldiers.
However, by Friday none had come forward raising fears of renewed bloodshed.
Hundreds of foreigners are believed to be sheltering in South Waziristan and other regions along the border with Afghanistan. Among them are Afghan refugees and Central Asian and Arab veterans of the anti-Soviet war in Afghanistan in the 1980s.
South Waziristan is widely believed to be a sanctuary for al-Qaida and Taliban fighters who have launched attacks in eastern Afghanistan and is a possible hideout for Usama bin Ladin and his deputy Ayman al-Zawahri.
"The extension is part of a political process, and we want to resolve the issue through talks"
Maj Gen Shaukat Sultan,
spokesman, Pakistan army
Pakistan is a key ally of the United States in its war on "terror", and US officials welcomed the March military operation - although it angered local people and failed to yield arrests of any senior al-Qaida figures.
The operation ended when tribal elders sought time to negotiate a deal between local fighters and the army which led to five powerful pro-al-Qaida leaders accepting an amnesty offer.
Since then, foreign fighters have not been seen in Wana, the main town in South Waziristan. Officials say they have moved to caves near the border with Afghanistan with light and heavy weapons.