Maulvi Omar was photographed in detention in Peshawar
Pakistan's army has arrested a man it believes to be the chief spokesman for the country's Taliban, officials say.
Maulvi Omar was a spokesman for the Tehrik Taliban Pakistan (TTP), one of the main Taliban groups in the country.
He was reportedly picked up in the Mohmand tribal area close to the border with Afghanistan, while travelling in a car with two associates.
Mr Omar is said to have been a key aide of Taliban leader Baitullah Mehsud, thought to have been killed recently.
Pakistani officials say they will produce Mr Omar before journalists later on Tuesday.
"A very, very important militant has been arrested," Maj Fazal Ur Rehman told the AFP news agency.
Despite that statement, correspondents say Maulvi Omar's importance has diminished in recent weeks because of army advances in his stronghold of Bajaur, in north-western Pakistan.
His arrest came as a senior Pakistani army officer said that it would take months to prepare an offensive against the Taliban in South Waziristan, where they are strongest.
Lt Gen Nadeem Ahmed was speaking after briefing the visiting US envoy to Afghanistan and Pakistan, Richard Holbrooke.
He said the army was short of "the right kind of equipment" in the offensive against militants in the north-west.
The arrest follows a concerted military offensive against the Taliban in the Swat valley region of Pakistan's North West Frontier Province.
Maulvi Omar comes from Bajaur, a tribal area in the North West where the Taliban established themselves early on.
Pakistani security forces have clashed with militants recently in nearby Mohmand, which is currently controlled by the Taliban.
The BBC's Aleem Maqbool, in Islamabad, says Maulvi Omar's detention will be seen as another success for the Pakistani military.
He was a senior aide to Baitullah Mehsud, and Pakistan will be hoping the removal of key leadership figures will plunge the Taliban into disarray, our correspondent says.
They are already on the back foot with the defeat in Swat and the reported death of Baitullah Mehsud, head of the organization.
Despite denials, there has been no clear proof yet from the Taliban that their leader is still alive.
While Maulvi Umar's position is not as vital, he is remains of significance primarily for two reasons.
He has been acting as a liaison between the various Taliban groups to settle differences.
Maulvi Umar also had strong connections in the media, and was a key figure in the Taliban's propaganda campaigns.
Correspondents say that his arrest may provide key information about the Taliban's recent operations and especially the mystery surrounding the status of Baitullah Mehsud.
Islamabad and Washington say Baitullah Mehsud was killed in a US drone attack earlier this month.
Nevertheless, the infrastructure through which militants have been recruited and trained remains in place.
There has been a surge of violence in the north-west since the army launched a summer operation to dislodge Taliban militants from their strongholds there.