New Dehli: India pointed a finger on Friday at Pakistani-linked "elements" for the deadly attacks in Mumbai, raising the prospect of a breakdown in the nuclear-armed rivals' peace efforts.
But Islamabad said it was not to blame, and, in an unprecedented step, agreed to let the head of the Pakistani military's Inter Services Intelligence (ISI) agency go to India to share information.
On Thursday, Indian Prime Minister Manmohan Singh pinned the blame for the Mumbai attacks on militant groups based in India's neighbours, usually an allusion to old rival Pakistan.
Indian Foreign Minister Pranab Mukherjee was more explicit on Friday. "Preliminary evidence, prima facie evidence, indicates elements with links to Pakistan are involved," Mukherjee told a news conference in New Delhi.
He urged Pakistan to dismantle the infrastructure that supports militants.
Pakistan has denied involvement and condemned the attacks. It has also offered full cooperation in fighting terrorism. "Pakistan is willing to cooperate at every level with the government of India," Pakistan's Foreign Minister Shah Mehmood Qureshi told reporters during a visit to New Delhi that was scheduled before the attacks.
"Whoever has done this is neither your friend nor our friend. We are not responsible for this, nor is it in our interest to get involved in something like this."
Relations between India and Pakistan have warmed in recent years, despite no progress on Kashmir.
The use of heavily armed "fedayeen" or suicide attackers in Mumbai bears the hallmarks of Pakistan-based militant groups such as Lashkar-e-Taiba or Jaish-e-Mohammed, blamed for the 2001 attack on India's parliament.
Both groups are outlawed in Pakistan. They made their name fighting Indian rule in disputed Kashmir and were closely linked in the past to the ISI.
Lashkar Taiba denied any role in the Mumbai attacks, and said it had no links with any Indian group. Instead, the little-known Deccan Mujahideen claimed responsibility.
But analysts said a link to Pakistani militants was plausible.
"There is no definitive evidence so far," said London-based political analyst and author, Farzana Shaikh. "But it wouldn't be entirely implausible, given that sections of Pakistan's intelligence agencies have in the past been linked to terrorist attacks.