Taleban leader Mullah Omar is living in Pakistan under the protection of its ISI intelligence agency, a captured Taleban spokesman has said.
Muhammad Hanif was seen sitting in a dimly-lit room
The spokesman, Muhammad Hanif, made the apparent confession to Afghan agents who videotaped the questioning.
Mr Hanif is seen sitting in a dimly-lit room telling agents that Mullah Omar is in the city of Quetta. Correspondents confirm the voice is his.
Mullah Omar has not been seen since 2001. Pakistan rejected the claims.
Pakistani Interior Minister Aftab Khan Sherpao told the Associated Press news agency the claim that Mullah Omar was in Quetta was "totally baseless".
"We have no information on the whereabouts of Mullah Omar. He is not living in Pakistan.
Mullah Omar (C) and Taleban leaders are still at large
"Afghan intelligence has made contradictory statements since the arrest of this so-called spokesman of Taleban. We don't know who this person is, and from where he had been arrested."
Afghanistan's intelligence agency distributed copies of the video CD to journalists on Wednesday.
Although the voice is confirmed as that of Mr Hanif, the conditions under which he made his statements are not clear.
He is sitting in the video and heard speaking in a soft voice.
Asked about Mullah Omar, he says: "He lives in Quetta."
"He is protected by the ISI," Mr Hanif adds, referring to Pakistan's Inter-Services Intelligence agency.
Afghan President Hamid Karzai made similar allegations last year.
Mr Hanif also alleges that former ISI head Hamid Gul is supporting the Taleban against Afghan and foreign troops.
The ISI was instrumental in backing the Taleban after civil war swept Afghanistan following the withdrawal of Soviet troops in 1989.
Afghan agents say they arrested Muhammad Hanif in the eastern province of Nangarhar near the border with Pakistan on Monday.
Two others travelling with him were also apprehended.
Nangarhar Governor Gul Aghar Sherzai said he had been picked up in a house which also contained what he described as packets of anthrax powder.
He did not say if the powder found was the deadly anthrax bacteria, or how much of it there was. Local intelligence officials and police would not confirm any discovery of anthrax.
Mr Hanif has been highly active over the past year, regularly e-mailing news organisations with the Taleban's version of events in the east of the country.
A man called Qari Mohammad Yousuf has performed similar functions for the Taleban in the south.
The two men were appointed after the capture in Quetta, Pakistan, of former Taleban spokesman Latifullah Hakimi in October 2005.
The Taleban have confirmed Mr Hanif's arrest.
On Wednesday, they named a replacement, Zabihollah Mojahed, the Peshawar-based Afghan Islamic Press reported.