Investigators probing the Malegaon blasts have picked up a number of persons for questioning and expect to solve the case shortly, a senior Home Ministry official said in New Delhi [Images] on Monday.

"The investigation into the Malegaon blasts is moving in the right direction," he said.

"We expect a solution to the case quickly," the official said.

The Centre was awaiting the report of the Central Forensic Science Laboratory on the type of explosives used to trigger the blasts in Malegaon that left 31 people dead and nearly 300 injured.

In Malegaon, police said the explosive devices used in Friday's attacks contained a mixture of RDX, ammonium nitrate and fuel oil.

A 10-member special investigation team is probing the blasts along with police in Nashik and the Mumbai-based Anti-Terrorist Squad.

Personnel from the ATS and National Security Guard joined forensic experts from Mumbai and Nashik to collect evidence from a mosque, a graveyard and the busy Mushaira Chowk, the three spots where the explosions occurred.

Samples of plastic bags, bicycles and boxes have been collected from the sites to ascertain the type of explosives used in the attacks.