At least 17 Taliban militants and a tribesman were killed in the latest clashes in Pakistani tribal regions bordering Afghanistan, officials said on Tuesday.
Pakistani jets killed five militants in the Bajaur tribal region on Tuesday, while artillery and mortar fires overnight killed 10 others, a security official told AFP.
Separately, two militants and a tribesman were killed during a gunbattle between militants and a tribal lashkar (force), he added.
The tribal force was formed last week to take action against militants hiding in the area, whom local tribesmen say are undermining their power structure.
There was no way to independently verify the tolls.
Almost 190,000 people have been displaced from the Bajaur region since fighting began last month, the United Nations refugee agency UNHCR said Tuesday.
"This number includes over 168,000 Pakistanis now sheltering in their country's North West Frontier Province and another 20,000 Pakistanis and Afghans who fled into eastern Afghanistan," said UNHCR spokesman Ron Redmond.
He said added that due to "security reasons", the agency did not have access to areas on both sides of the border where most of the displaced were staying with families.
Pakistan said in late September that the fighting in Bajaur was some of the heaviest since Pakistan joined the US-led "war on terror" in 2001.
It said it had killed 1,000 militants, including Al-Qaeda's operational commander in the region, Egyptian Abu Saeed Al-Masri, since early August.
Also on Tuesday Pakistani police questioned a man they said was a US national arrested near the Afghan border. The man was dressed as a local and had no travel documents, police said.
"Officers arrested a young American national as he was entering the Mohmand tribal region on Monday evening," local policeman Khurshid Khan told AFP.
"The bearded man was aged 20-25 and wore a traditional Pakistani shalwar kameez. He said he was visiting a friend." Police said he told them that he was an American from Florida.
He was taken to Peshawar for questioning as foreigners are required to have a special permit to enter the tribal belt. A spokesman for the US embassy said he was unable to confirm reports of the arrest.
The US and Afghan governments say Islamic militants use the remote border areas of Pakistan to launch attacks on international coalition troops deployed in Afghanistan.
Al-Qaeda chief Osama bin Laden and his deputy, Ayman al-Zawahiri, are widely believed to be hiding in the mountainous region.