MOSCOW: Uzbek fighters from an Al-Qaeda-linked militant organisation have thrown their support behind the militant Islamic State (IS) group controlling swathes of territory in Syria and Iraq.

A top leader for the Islamic Movement of Uzbekistan (IMU), an ally of the Taliban that has been mainly based in Pakistan's tribal belt since the US-led invasion of Afghanistan in 2001, announced its backing for IS.

“Hereby, on behalf of all members of our movement, in line with our sacred duties, I declare that we are in the same ranks with the Islamic State in this continued war between Islam and [non-Muslims],” Usman Gazi wrote in an online statement on Sept 26.

Gazi praised the Islamic State for its refusal to recognise state borders and said he hoped the group would soon take control of Palestine and the Muslim holy cities of Makkah and Madina.

“Islamic State is free from the patriotic or nationalist agenda ... you can see Arabs, Chechens, Uzbeks, Tajiks, Kyrgyz, Russians and many English-speaking Muslim mujahidin (fighters) in its ranks,” Gazi said.

Know more: Pakistani Taliban declare allegiance to IS militants

Set up in the late 1990s, the IMU is listed as a terrorist group by the United States. According to the United Nations, some of its leaders have held top positions in Al-Qaeda.

The group claimed its fighters were involved in a brazen attack on the international airport in Karachi, Pakistan, that killed 37 people in June.

Extremist group IS has seized large parts of Syria and Iraq, declaring a “caliphate” in June and imposing its harsh interpretation of Islamic law.

The group has been accused of carrying out widespread atrocities including mass executions, abductions and torture, as well as forcing women into slavery.

It is currently facing a campaign of air strikes by a US-led coalition that includes Britain, France and a number of Arab countries.