NEW DELHI (Reuters) -- The sophistication of the Mumbai attack points to the involvement of "state actors" in Pakistan, India's home minister has said ahead of a visit to the United States with a dossier of evidence.
Home Minister P. Chidambaram's comments are at odds with Pakistan's insistence that nonstate actors were behind the coordinated strike by 10 gunmen that killed 179 people in Mumbai and has inflamed tensions between the South Asian neighbors.
"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 nonstate 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 in the coming days.
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 neighbors that have fought three wars since 1947 and regularly accuse the other of fomenting trouble in their territory.
But, despite a near-daily war of words between the countries and military muscle flexing, most analysts say fear of Indian strikes on suspected militants targets in Pakistan, which could spark war, was easing.
Pakistani Foreign Minister Shah Mehmood Qureshi said tension had diminished.
"The situation has been defused from before," Qureshi told reporters in the city of Multan. "Some positive Pakistani proposals and the role of our friends and important powers in and outside the region have contributed positively."
Qureshi said U.S. Assistant Secretary of State Richard Boucher would be visiting and they would meet on January 5.
Pakistan, which has in the past used militants to further foreign-policy objectives, condemned the Mumbai violence and launched raids on militants 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 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 from the town of Faridkot.
Chidambaram, referring to a Pakistani media report that a man who said he was Kasab's father had been located in the town, said a DNA test could determine the truth.
Chidambaram said India now wanted "cast-iron guarantees" that no state or nonstate actor would be allowed to use Pakistani soil or resources to attack India.
"The price they will pay if this is repeated will be enormous," Chidambaram said, in the sternest warning yet to Pakistan.