The module of Indian Mujahideen and the Students Islamic Movement of India, which carried out bomb blasts in Delhi a week ago was also responsible for explosions in Varanasi and Gorakhpur.
Investigations into the Delhi blasts have revealed that Atif, who was killed in an encounter in Delhi on Friday, had himself planted bombs at the marketplace in Varanasi on March 7, 2006, while his accomplices Malik and Junaid had placed explosives at the Sankatmochan temple and railway station respectively.
Atif along with his accomplices Saif and Salman had a role in the Gorakhpur blasts in May 2008 where explosives were placed in milk containers.
"Atif and Saif planted bombs in the market in Varanasi, while Junaid placed the explosives at the railway station," Delhi Police Joint Commissioner (special cell) Karnal Singh told reporters in Delhi.
The probe also unveils the linkages of the Delhi bombers with Pakistan-based Lashkar-e-Tayiba, he said, adding that Atif, the point person of the Indian Mujahideen was in constant touch with Tauqir of SIMI.
"The LeT has linkages with HuJI and SIMI," Karnal Singh said.
A laptop, believed to belong to Atif, also had photographs of Tauqir and video clips of the Ahmedabad blasts, which were sent in emails shot off to various media organisations.
The Delhi police is sharing information with its counterparts in Uttar Pradesh, Karnataka, Rajasthan and Gujarat, Karnal Singh said.