The Islamic group carried out the attack April 30 with explosives and bladed weapons. (Agencies)
According to SITE, which tracks internet communication of suspected terrorist groups, the Islamic group released a video in which they are seen preparing a bomb hidden in a bag.
According to the group, this bomb was used in the attack, in which three people died and 79 were injured.
The claim supports the Chinese authorities, who said the attack was carried out by two religious extremists who died in the explosion.
The Xinjiang region often sees confrontation between authorities and extremist groups, many of them led by the people of Uyghur ethnicity.
The Uyghur ethnic group is one of the majorities in the area and seeks independence of the region as "East Turkestan".
In the last few months, several attacks on civilians have also taken place in busy train stations, which are also linked to Xinjiang-based terrorist groups by Beijing.
In an attack March 1, the worst of these attacks, 33 people (including four attackers) died and more than 140 were injured in the train station of Kunming in southern China.
Xinjiang shares its border with Afghanistan and Pakistan, and is home to many Muslim ethnic groups linked to the people of Central Asia, such as Uyghurs.
According to the Chinese government, the terrorist groups operating there are linked with the radical Islamic organisation Al Qaeda.
However, exiled Uyghur groups accuse Beijing of using terrorism as an excuse to surpass their religion and culture.
In July 2009, ethnic conflicts between Uyghurs and Chinese Han (majority in the country) claimed more than 200 lives in Urumqi, the worst ethnic violence in China in decades.
The Islamic group carried out the attack April 30 with explosives and bladed weapons.