WASHINGTON: World's most wanted terrorists Osama bin Laden and his deputy Ayman al-Zawahiri may be hiding close to each other in houses in northwest Pakistan, protected by some members of ISI , a media report said on Monday.The two top al-Qaida commanders may not be together and are not living in caves as forseen by American experts to evade detection, the CNN reported quoting a top NATO officer based in Afghanistan."Nobody in al-Qaida is living in a cave," said the official, who declined to be named because of the sensitivity of the intelligence matters involved, CNN said.Rather, al-Qaida's top leadership is believed to be living in relative comfort, protected by locals and some members of the Pakistani intelligence services ISI, the official said.Pakistan has repeatedly denied protecting members of the al-Qaida leadership.The official said the general region where Osama is likely to have moved around in recent years ranges from the mountainous Chitral area in the far northwest near the Chinese border, to the Kurram Valley which neighbors Afghanistan's Tora Bora, one of the Taliban strongholds during the US invasion in 2001.Tora Bora is also the region from which Osama is believed to have escaped during a US bombing raid in late 2001. US officials have long said there have been no confirmed sightings of Osama or Zawahiri for several years.The area that the official described covers hundreds of square miles of some of the most rugged terrain in Pakistan inhabited by fiercely independent tribes.The official also confirmed the US assessment that Mullah Omar, the leader of the Taliban, has moved between the cities of Quetta and Karachi in Pakistan over the last several months.The official would not discuss how the coalition has come to know any of this information, but he has access to some of the most sensitive information in the NATO alliance.Pakistan's interior minister Rehman Malik today said that similar reports of bin Laden and Mullah Omar's whereabouts have proven false in the past.Malik denied the two men are on Pakistani soil, but said that any information to the contrary should be shared with Pakistani officials so that they can take "immediate action" to arrest the pair, CNN reported.The NATO official said hard core Taliban groups such as the Quetta Shura run by Mullah Omar, the Haqqanis, the HiG (Hezb-e-Islami Gulbuddin) and the Pakistani Taliban still could potentially muster as many as 30,000 fighters.