Pakistani forces traded sporadic gunfire with militants overnight Thursday in a tribal region near the Afghan border known as an Al Qaeda (search) hideout, a day after heavy fighting killed at least 20 gunmen, officials said.

The clashes follow weeks of failed efforts to get militants in South Waziristan (search) to surrender peacefully since an army counterterrorism offensive in March that left 120 people dead.

Army spokesman Maj. Gen. Shaukat Sultan said troops and militants exchanged intermittent gunfire through the night, but the situation was calm on Thursday morning.

Brig. Mahmood Shah, chief of security for Pakistan's tribal regions, said foreigners and local tribesmen had been holed up in four fortress-like houses in the Ghat Ghar (search) area, about 25 miles from the Afghan frontier.

He said late Wednesday that about 20 foreign militants and one paramilitary soldier had been killed, and three civilians had died in the crossfire.

An army statement said earlier that the bodies of eight militants, some of them foreigners, had been retrieved and one wounded militant captured. It gave no details of their identities or nationalities.

Army spokesman Maj. Gen. Shaukat Sultan refused to disclose how many casualties the army and paramilitary forces had suffered. He declined to comment on a report Thursday in Pakistan's leading English language daily, The News, that 17 troops died.

"There are certain casualties on the security forces but I cannot give details," Sultan told The Associated Press.

The remoteness of the location and roadblocks prevented journalists from gaining access to the area or confirming casualties.

Pakistan's tribal areas bordering Afghanistan are a possible hideout for Usama bin Laden (search) and his chief aide, Ayman al-Zawahiri (search). There was no immediate indication that top Al Qaeda figures were among those involved in the latest fighting.

Tension has been building in South Waziristan over the past month as authorities have pressured tribesmen to evict hundreds of Central Asian, Arab and Afghan militants, many of whom moved there from Afghanistan after the fall of the Taliban regime in late 2001.

The militants have refused to register with authorities despite a government amnesty offer that would allow them to settle in Pakistan if they renounce terrorism.

The army and President Gen. Pervez Musharraf — a key U.S. ally in its war on terrorism — have warned that another military operation could be launched unless the foreign militants give themselves up.