"The NSG DG has informed that a body with circuit has been found from one of the sites. The body was found near the explosion site. We are not ruling out anything," he told reporters here.
Singh was replying to a question about the possibility of the involvement of a suicide bomber in Wednesday's blasts as the body was found with a circuit near one of the blast sites.
"The investigation is still on," he said.
The Home Secretary said explosive experts of Central Forensic Science Laboratory, NSG and Mumbai Police were examining the blast sites and according to the information available, ammonium nitrate was used for carrying out the blasts.
"The bombs were not crude and it is believed that trained persons were involved in making the bombs," he said. He said of the 133 hospitalised, condition of 23 people was serious.