ISLAMABAD  - The Islamic Movement of Uzbekistan (IMU), an Al-Qaeda affiliate that has been mainly based in tribal belt since the US-led invasion of Afghanistan in 2001, claimed the killing of 10 of their fighters during this week's assault in a statement posted on various Taliban-linked websites.

The attack extinguished a nascent peace process.

"At midnight of Monday ten ….mujaahids of Islamic Movement of Uzbekistan wearing their explosive-filled vests attacked a very special section of Karachi International Airport of Pakistan," the English-language statement attributed to IMU said.

The Pakistani security forces had taken of the attackers down, on on being cornered some of the militants had chosen to take the desperate measure of blowing selves up.

The IMU page included photographs of 10 black-turbaned fighters wearing green tunics and white trainers while carrying assault rifles, in what appeared to be a snowy mountainous region.

"This …operation was carried out as the revenge to the latest full-scale bombardments and night attacks with fighter jets by (the) Pakistan….Army," the statement added. A senior Pakistani Taliban official confirmed that Uzbek fighters were involved in the attack but did not say how many.

He told AFP: "Yes, the attack on the Karachi airport was a joint operation of TTP and Islamic Movement of Uzbekistan.

"……..we can't elaborate on how many Uzbeks and how many Pakistanis participated in this action," he added. A senior security official indicated that the group was partly Uzbek and partly Pashtun, while a second intelligence official in Karachi said the attack may have been coordinated with the help of a local group, the sectarian militant outfit deeply embedded in Pakistan's major cities. "We believe that the LeJ has coordinated the attacks," the Karachi official said.

Karachi police meanwhile announced Wednesday they would press murder and terrorism charges against Taliban spokesman Shahidullah Shahid, 10 "unknown" attackers and accomplices, in what was seen as a symbolic move.

Ten heavily armed militants laid siege to Karachi airport throughout Sunday night and the early hours of Monday morning in one of the most brazen attacks on a key installation in recent years.

Security analyst Imtiaz Gul said IMU fighters had migrated to Pakistan's tribal areas after being forced to flee from Afghanistan following the US-led invasion.

"They have been under the protection of the Pakistani Taliban for some time. The Uzbeks are dependent on them for shelter and survival and are used as their foot soldiers in operations," he said.

Foreign militants, mostly Uzbeks and Chechens are believed to have been involved in other major attacks in recent years, including on a Karachi naval base in 2011 and the military headquarters in 2009.