The North Waziristan tribal area bordering Afghanistan has been the scene of military attacks this month in which officials say nearly 200 pro-Taliban fighters have been killed.
Officials have blamed unrest in the region on Afghans, thought to number several thousand, who first moved there when the Soviet Union occupied their country in the 1980s.
On Monday, local state radio broadcast messages saying the Afghans must go.
Zaheerul Islam, a leading government official in North Waziristan, said Afghans had been given deadlines to leave two or three times last year but had not done so.
"Now they are not Afghan refugees but foreigners and must leave North Waziristan immediately," he said.
"Severe action will be taken if they don't do so."
Many Afghans in North Waziristan have built homes and set up businesses in the area. Others work as farm labourers.
Monday was the second day of relative peace in Miranshah, the capital of North Waziristan, after the Pakistan military said security forces had killed up to 30 pro-Taliban fighters and their supporters in a village about 10km (six miles) to the west on Friday night.
A curfew imposed nine days ago was further relaxed on Monday, allowing people to leave their homes for eight daylight hours to shop for essential provisions, but many shops remained closed.
Many residents who fled their homes after the violence started this month returned when the authorities relaxed the curfew on Friday.
"We are coming back because it is peaceful now," one said.
Announcements made via loudspeakers on government vehicles and from mosques urged government employees, teachers and bank employees to return to work.
Pakistani forces have been trying to remove foreign fighters from Waziristan since 2004. The latest violence started just before a visit to Pakistan by George Bush, the US president, on 3 and 4 March.
Many Pashtun tribesmen, who live on both sides of the border, sympathise with the Taliban and al-Qaida. Al-Qaida leaders Osama bin Laden and Ayman al-Zawahiri are believed to be hiding somewhere in the frontier region.