The video showed Humam Khalil Abu Mulal al-Balawi, cultivated by the CIA as an asset against al-Qaida - sitting with Mehsud’s successor in an undisclosed location.

It is believed to confirm the Pakistani Taliban’s claim of responsibility for one of the worst attacks in CIA history, though analysts said al-Qaida and Afghan militants are also likely to have played a part.

Speaking in Arabic in the video shown on al-Jazeera, the Arabic network, and Aaj, a Pakistani channel, al-Balawi noted that the Pakistani Taliban had given shelter to “emigrants” - Muslim fighters from abroad.

Mehsud, the group’s longtime leader, was killed in August by a CIA missile strike.

“We will never forget the blood of our emir Baitullah Mehsud,” said al-Balawi, who wore Afghan dress on the 1 1/2 minute video. “We will always demand revenge for him inside America and outside.

“It is an obligation of the emigrants who were welcomed by the emir.”

The 32-year-old al-Balawi was apparently a double agent - perhaps even a triple-agent - with links to al-Qaida, the CIA and Jordanian intelligence.

He was invited inside the CIA facility in Afghanistan’s eastern Khost province bearing a promise of information about Ayman al-Zawahri, al-Qaida’s second-in-command.

Instead, he blew himself up in a meeting on December 30, killing seven including the CIA’s base chief.

In the video, al-Balawi appeared to mock assertions that U.S. or Jordanian intelligence had employed him.

“The emigrant for the sake of God will not put his religion on the bargaining table and will not sell his religion even if they put the sun in his right hand and the moon in his left,” he said, a reference to a verse in the Quran.

Al-Balawi ended the clip by saying the Pakistani Taliban under the leadership of the new chief, Hakimullah Mehsud, would fight till victory. IntelCenter, a U.S.-based group monitoring extremist sites, said the video was released by the Pakistani Taliban.

The CIA attack would be the most prolific strike on a U.S. target by the Pakistani Taliban under Hakimullah Mehsud’s watch. It is also unusual because the Pakistani Taliban rarely claim responsibility for strikes in Afghanistan.

Statements by Afghan Taliban and al-Qaida leaders since the attack have confused the issue of who backed the plan.

Mahmood Shah, a former security chief for Pakistan’s tribal regions who has deep contacts in the nation’s army, said although the Pakistani Taliban likely played a major role, al-Qaida probably masterminded the attack.

The Haqqani network, a highly autonomous Afghan Taliban faction, probably also gave consent because it controls much of Khost.

“It shows the close coordination between al-Qaida and the Pakistani Taliban,” Shah said, noting that the extent of those links had at times been downplayed, even though analysts generally agree that Islamist militant groups in the region are increasingly intertwined.

Though linked, the Pakistani Taliban and the Afghan Taliban are separate movements.

The Afghan Taliban are focused on ridding Afghanistan of Western troops and toppling the U.S.-backed government in Kabul, while the Pakistani Taliban are primarily determined to overthrow the U.S.-allied government in Islamabad.

But both militant movements are largely driven by Pashtuns, an ethnic group that straddles both sides of the Afghan-Pakistan border and whose members easily slip back and forth between the countries.

A major Pakistani army offensive in South Waziristan tribal region is believed to have forced many Pakistani Taliban leaders to go on the run to other parts of the lawless tribal belt along the Afghan border.

Though the group initially appeared to be in disarray after the August missile strike and the offensive, it and linked militant groups are suspected in a rising tide of violence in Pakistan since October.

More than 600 people have died in a range of suicide and other bombings across the nuclear-armed country.

The secretive eastern Afghan CIA base that was attacked was reportedly was used as a key outpost in the effort to identify and target terror leaders, many of whom were taken out by the drone-fired missile strikes.

Despite the suicide bombing’s blow to the CIA, there has been been no letup in missile strikes on Pakistan’s tribal regions, where many of the top terror leaders including Osama bin Laden are believed to be hiding.

There have been at least five such missile strikes in North Waziristan since the bombing in Khost.