Investigators are suspecting the hand of illegal Bangladeshi migrants in Saturday's blast in a south Delhi [Images] market, saying it does not have the signature of the serial explosions carried out by the Indian Mujahideen [Images] in the national capital and other cities.

Preliminary analysis of the bomb exploded in the Mehrauli market showed that the explosive was made of a mixture of ammonium nitrate and ammonium chloride and no timer device or detonator was used to trigger the blast, the police said.

"It might be the handiwork of a fanatic group. It might be that of a criminal gang who illegally migrated from Bangladesh. We are looking into it," a top Delhi police official said.

Police suspect that the aim of the those behind the blasts was to create tension in the locality during Ramzan and the approaching Dusshera.

Investigators are also looking into the "continuity factor" of the blast as south Delhi had witnessed at least five similar low-intensity blasts this year.

Today's explosion was not carried out in a "sophisticated" manner as was evident from the way in which the bomb was assembled and placed in the market, the official said.

Almost ruling out the involvement of Indian Mujahideen in the incident, another official said, "It was a crude bomb. It was loosely packed and so the intensity was low and look at the manner in which they planted the bomb."

The official said the chances of Indian Mujahideen's involvement in the Mehrauli blast are "very low", pointing out that the terror outfit had not claimed responsibility for the blast, as it did in previous occasions.