Investigators probing the July 13 Mumbai serial blasts have got strong leads and made headway in the past few days,sources indicated on Thursday. Mumbai Police teams have fanned out across the country and gleaned concrete leads from Pune and Parbhani in Maharashtra and from Gujarat,the sources said. Teams were sent to Karnataka,Andhra Pradesh, Madhya Pradesh,Delhi,Rajasthan,Bengal,Uttar Pradesh, said an officer involved with the probe who did not want to be named. There are now strong leads in Parbhani,Pune,and in Gujarat. Significant headway has been made in the investigations. The probe is at a crucial juncture. Certain radical elements picked up from different locations over the past week,though not directly involved in the blasts,had reportedly provided information that corroborates the line of investigation being pursued by the police,the sources said. Union Home Secretary R K Singh seemed to confirm this. There is important progress in Mumbai, he told PTI in Thimpu when asked whether there had been any breakthrough in the probe into the blasts. He said investigation was on the right track,but refused to elaborate. Senior ATS and Crime Branch officers,however,were tight-lipped about recent developments in the probe. There was no clarity on who was behind the blasts. But sources said that while involvement of a new and smaller outfit was being probed,the needle of suspicion had initially pointed towards Indian Mujahideen.