New Delhi, July 14 (IANS) Investigating agencies have identified the two-wheeler in which one of the bombs of Wednesday's Mumbai serial blasts had been planted, Home Secretary R.K. Singh said Friday. Eleven CDs of CCTV footage were also being scanned for clues into the serial bombings, he added.

The country's top security official said cyber experts were tracing the origins of an e-mail that may give the investigators a clue about the bombings Wednesday evening that killed 17 people and left 131 injured.

"We have identified the scooter in which one of the bombs was planted," Singh said on the sidelines of a function here.

Asked if the investigators had any definite lead, the home secretary said several suspects were being questioned because of their "previous known linkages" with terrorists.

"There are various leads based on our previous databases, various people are being questioned, so investigation is going on," he said.

He was asked if investigators had traced any cross-border links to the triple bombings. The home secretary said: "We have an e-mail which originated elsewhere. It is being followed up."

About the CCTV footage for clues into the bombings, Singh said: "There are about 11 CDs (of CCTV footage) which have to be gone through. It's voluminous work."

"Now, we have all the people and the faces appeared. They have to be recognised to see whether they are locals or outsiders. That process is on. People who are not recognised have to be put through a data base... the suspicious people are being verified."