The sophistication of the Mumbai attack points to the involvement of "state actors" in Pakistan, India's home minister said on Sunday, ahead of his next week's visit to the United States with a dossier of evidence.
Home Minister P. Chidambaram's comments are at odds with Pakistan's insistence that non-state actors were behind the coordinated strike by 10 gunmen that killed 179 people in Mumbai and has inflamed tensions between the South Asian neighbours.
"Somebody who is familiar with intelligence and who is familiar with commando operations has directed this operation," Chidambaram told NDTV news channel.
"And that cannot entirely be a non-state actor. In fact, I presume they are state actors or state-assisted actors unless the contrary is proved," he added.
"It was too enormous a crime and required very elaborate planning, communication networks, financial backing. It was a very, very sophisticated operation."
Chidambaram said the evidence was "overwhelming" and "unanswerable" and would be shared with the United States.
Indian officials said Chidambaram could meet top U.S. Homeland Security officials and possibly also Secretary of State Condoleezza Rice and members of President-elect Barack Obama's transition team.
"It is a detailed dossier, supported by electronic evidence like transcripts and intercepts and interrogation reports," Chidambaram said.
India has blamed Pakistan-based militants for the attack in Mumbai which has revived hostilities between the nuclear-armed neighbours that have fought three wars since 1947 and regularly accuse the other of fomenting trouble in their territory.
Pakistan, which has in the past used militants to further foreign policy objectives, condemned the Mumbai violence and launched raids on militants on its soil in the face of global outrage. But the action has not satisfied India.
New Delhi wants Islamabad to dismantle what it says are terrorist training camps on its territory, and extradite at least 40 suspects. Pakistan says it will act if India provides proof.
India says it has evidence that shows the Mumbai attack plot was hatched in Pakistan and Islamist militants took orders from their handlers across the border as they fought Indian commandos.
Police say Mohammed Ajmal Kasab, the sole Mumbai attacker arrested alive, has confessed to being a Pakistani national.
"Today we have Ajmal Kasab in our custody... his DNA is available... now there is a person in Faridkot village in Pakistan who says 'I am his father...' his DNA is available in Pakistan," Chidambaram said.
"So if somebody matches the DNA...we will know who is right and who is wrong."
Chidambaram said India now wanted "cast iron guarantees" that no state or non-state actor would be allowed to use Pakistani soil or resources to attack India.
"The price they will pay if this (Mumbai incident) is repeated will be enormous," Chidambaram said, in the sternest warning yet to Pakistan.
But, despite a near-daily war of words between the two countries and military muscle flexing, most analysts say fear of Indian strikes on suspected militants targets in Pakistan, which could spark war, was easing.Reuse content