The Mumbai Police on Wednesday claimed a major headway in the serial train blasts probe with the preparation of over half a dozen sketches of suspects involved in Tuesday's blasts, sources said.

"The sketches have been prepared after getting details from an eyewitness and scores of persons injured in the blast," a senior crime branch official told PTI in Mumbai.

The sketches will be distributed among all crime branch units and special teams of the Anti Terrorism Squad formed to probe the blasts, sources said.

The sketches are unlikely to be released to public to maintain confidentiality of the probe, sources added.

Meanwhile, Commissioner of Police A N Roy asked crime branch men to contribute in the probe, and assist the ATS, which has been assigned the task.

Joined by senior police officials including Joint Police Commissioners, Arup Patnaik (Law & Order) and Meera Borwankar (crime), the police chief asked crime branch officials to contribute by providing clues in the case.

"Besides the ATS, the crime branch is also likely to undertake an independent probe into the blasts using its in house expertise in tackling the underworld," an official said.

Meanwhile, all the former crime branch officials who were associated with the investigations of previous blasts in Mumbai, are likely to be asked to join the investigations and are likely to be assigned individual responsibilities, the official further said.