Suspecting the use of high-grade explosives and detonating mechanism in blasts that rocked Mumbai on Monday, expert teams from the National Security Guard and army have been flown to the metropolis to help in investigations.

While the investigations are at a preliminary stage, NSG and army bomb experts do not rule out the possibility of use of RDX or semtex, keeping in view the broad expanse of the areas devastated in the twin blasts and the similarity of their use by terrorists in other parts of the world recently.

Experts said the impact of the blast near Gateway of India, where less people had died as the area was not overcrowded, had been felt at least 70 to 90 metres away, shattering windowpanes of Taj Hotel.

The NSG and army experts would help the state police in investigations to determine the type of explosive used as well the detonating mechanism.