"Scores of Taliban raided Mandal Daag village in the Matta district of the valley to abduct Pir Samiullah," the official told the AFP news agency.
Samiullah, who leads a 500-strong armed group of local people, and his supporters have demanded that the Taliban leave the valley.
Fazlullah has campaigned for a stricter interpretation of sharia in the Swat valley region.
The fighting in Swat came as fresh fighting was reported in the Bajaur tribal region bordering Afghanistan.
Pakistani forces had claimed a rare succes in the region by retaking the town of Loi Sam, but on Sunday fighting continued with helicopters and artillery pounding targets in Bajaur.
Jamil Khan, a Pakistani official, said that eight anti-government fighters had been killed in the latest fighting in Bajaur.
Khan said reports from the region indicated several others had suffered injuries in the latest assault, but he gave no information about troop or civilian casualties.
Major-General Tariq Khan, a spokesman for the military, said government forces captured Loi Sam earlier this week "and killed the militants who were hiding there".
Reports said that nearly 200,000 civilians have fled the fighting in the town.
Kamal Matinuddin, a retired general and former ambassador to Thailand, said that there was a prospect of civilians being hurt by the fighting.
"It so happens that the militants that are in these tribal areas, particularly in Bajaur, are finding some shelter in the houses there. The job is becoming very difficult for the Pakistan army to avoid civilian casualties," he told Al Jazeera.
"Although the Pakistani army has called for civilians to leave the area so that they can carry put their military operations more successfully, unfortunately there are some civilian casualties occurring even now.
"But the fact remains that the Pakistan army has the support of the elected government and is determinted to carry out its objective in eliminating the militants from the tribal areas. They have achieved a certain amount of success."
Pakistan's tribal regions are considered a stronghold for the Taliban and al-Qaeda.
The army launched its offensive in Bajaur in early August, saying the region had become a "mega-sanctuary" for fighters who had set up a virtual mini-state.
Khan said troops had by Saturday overrun the area and were in "complete control" of the town, though he forecast it could take between six months and a year before authorities could gain complete control of Bajaur.
But some analysts criticised the military move.
"This is not the first time that the military or the Pakistani government has claimed that they have captured an important person or claimed to have attacked and been successful in destroying the sanctuary of the Taliban," Khalid Rahman, the director general of the Institute of Policy Studies in Islamabad, told Al Jazeera.
"Perhaps the whole strategy is not correct ... I am really afraid that this military strategy is going to increase the problem, unless it is accompanied by a genuine, sincere dialogue."
Talks are meanwhile expected to take place in Islamabad on Monday between Pakistani and Afghan political leaders with an aim to end violence in the border regions. Ethnic Pashtun tribal chiefs are also expected to participate.
The meeting, dubbed a Pakistan-Afghanistan "Jirgagai", or mini-jirga, is a follow-up to a grand assembly in Kabul last year in which delegates called for talks with Taliban fighters.
Around 50 political leaders, Pashtun elders and Muslim clerics from both countries will discuss growing violence by al-Qaeda and the Taliban fighters on both sides of their disputed border.
"The two main objectives of the jirgagai are to expedite the ongoing dialogue process with the opposition and monitor implementation of decisions of the (Kabul) jirga," Mohammad Sadiq, a Pakistani foreign ministry spokesman, said.
But critics say the mini-jirga will be little more than a talking shop without the participation of representatives of the Taliban.