Menon is expected to leave for the US on Monday. His office could not be contacted.

The terror attacks on Mumbai have thrown up crucial evidence which needs to be brought to the urgent notice of Americans in view of India's past experience with Pakistan.

According to a source in government, "We have three pieces of evidence right now of the involvement of people based in Pakistan. One is the satellite phone through which calls were made to Pakistan from Mumbai. Two, the interrogation statement of the captured terrorist has lots of details which will help demolish Pakistan's claims that there are no terrorist camps inside Pakistan. Three, the dead bodies of nine terrorists and the proof of identity found on them."

The Indian side believes that as has happened in the past, Pakistan is likely to say on seeing the details of telephone numbers and their possible owners' names that no such numbers exist and there are no such telephone owners.

The Americans have a highly sophisticated "call-chaining" technology that will help trace the entire sequence and chain of telephone calls made through satellite. India also possesses the telecommunications technology, but the US-based system is more advanced.

The Lashkar e Tayiba's senior operative, Yousuf Muzamil, who masterminded the Taj Mahal hotel [Images] operation, had coordinated the logistics with the help of Yahya Mujahideen [Images] who is based in Bangladesh.

The US is expected to help India get more names through "call chaining" technology.

India, however, needs to fine-tune the evidence gathered so far in Mumbai.

"America could be a positive help," said the source.

More important, it is felt, is to apprise the US about the anger and anguish within India which can't be ignored by any government.