Police have detained about a dozen people in connection with a deadly bomb blast in a crowded New Delhi market, officials said on Sunday, the second attack in the capital this month.

Police said they had witnesses who could identify the two men who dropped a plastic bag in the capital's busy Mehrauli market, before speeding away on a motorcycle on Saturday.

A boy picked up the bag and ran after the motorcyclists to return it when there was a huge explosion, killing him on the spot. A 60-year-old man died in hospital later. Twenty-two people wounded.

"We are interrogating a lot of people for clues and should come up with some answers soon," Rajan Bhagat, the Delhi police spokesman said on Sunday.

In Haryana, police detained two people in connection with a threat about possible bomb blasts made to Delhi police last Friday.

Saturday's explosion followed a blast in the capital on Sept. 13 that killed 23 people and wounded 100.

The Indian Mujahideen (IM) militant group, an offshoot of the banned Students' Islamic Movement of India, claimed responsibility for that blast.

Police said they were investigating possible links between blast and the Indian Mujahideen group, which they say is connected with Pakistani militant group Lashkar-e-Taiba and Bangladesh's HUJI group.

They said illegal Bangladeshi migrants with the support of some militant groups like HUJI could be behind the blast.

Investigators said ammonium nitrate, sulphur and potassium were possibly used with nails to cause the low-intensity blast on Saturday.

Police said a woman, who said she spoke to the suspects minutes before the blast, was being questioned.

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