India strongly suspects Pakistani hand in Tuesday's serial blasts in Mumbai suburban trains with all leads pointing to involvement of Inter Services Intelligence-backed terrorist outfit Lashkar-e-Tayiba, highly placed sources said on Thursday night.

"The involvement of Pakistani hand is obvious... There is no doubt that LeT, which is backed by Pakistan's ISI, is involved," the sources told PTI.

Various agencies investigating the serial blasts are also probing whether other terror groups were involved along with LeT, they said.

"Other terror groups may have been involved in the blasts along with LeT... This angle is being investigated," the sources said.

The progress in the probe into the blasts was discussed at a meeting of the Union Cabinet chaired by Prime Minister Manmohan Singh [Images] on Thursday.

Dr Singh is scheduled to visit Mumbai on Friday for a first-hand assessment of the situation in the wake of the bombings that have left 200 dead and over 700 injured.