Islamabad:  Pakistan will not turn over the Afghan Taliban's No 2 leader and two other high-value militants captured this month to the United States, but may deport them to Afghanistan, a senior minister said on Friday.

Interior Minister Rahman Malek said Pakistani authorities were still questioning Mullah Abdul Ghani Baradar, the most senior Taliban figure arrested since the start of the Afghan war in 2001, and two other senior militants arrested with US assistance in separate operations this month.

If it is determined that the militants have not committed any crimes in Pakistan, they will not remain in the country, he said.

"First we will see whether they have violated any law," Malek told reporters in Islamabad. "If they have done it, then the law will take its own course against them.

"But at the most if they have not done anything, then they will go back to the country of origin, not to USA," Malek said.

Pakistani authorities working with the CIA arrested Baradar about two weeks ago in the southern city of Karachi, Pakistani and US officials have said. At about the same time, Pakistani security forces picked up Taliban "shadow governors" for two Afghan provinces, Afghan officials said.

A series of raids by Pakistani forces have followed, netting at least nine Al Qaida-linked militants who were sheltering in Pakistan. Missiles fired from a US unmanned drone aircraft on Thursday killed the brother of Afghan Taliban commander Siraj Haqqani, intelligence officials said.

Taken together, the crackdown could be the most significant blow to the militants since US-led forces invaded Afghanistan in 2001 to oust the hard-line Islamist Taliban regime for sheltering Osama Bin Laden and the Al Qaida network responsible for the September 11 attacks.

Pentagon spokesman Geoff Morrell said the US was pleased with the recent arrests. He declined to say whether they were the result of better intelligence or an increased willingness by Pakistan to go after suspected militants.

"What I will say to you, yet again, is that we are enormously heartened by the fact that the Pakistani government and their military intelligence services increasingly recognise the threat within their midst and are doing something about it," Morrell said.

Some of those caught in the recent operations are key figures in the Afghan insurgency, while others are members of militant groups that operate just across the border in Pakistan.

Among those arrested were Ameer Muawiya, a Bin Laden associate who was in charge of foreign Al Qaida militants in Pakistan's border areas, and Akhunzada Popalzai, also known as Mohammad Younis, a one-time Taliban shadow governor in Zabul province and former police chief in Kabul, according to Mullah Mamamood, a tribal leader in Ghazni province.