Indian Prime Minister Manmohan Singh told President Pervez Musharraf that there were indications Saturday's blasts in the Indian capital had links with Pakistan-based groups, India's Foreign Ministry said.
Singh made the comments when Musharraf called him to offer his condolences for the death of 59 people, killed on Saturday when bombs exploded at two busy Delhi markets, a statement said.
"The Prime Minister told the President of Pakistan that the country was outraged at these heinous acts of terrorism," the foreign ministry statement said.
"Violence against defenceless civilians can never be justified, the Prime Minister said, and terrorism would never weaken India's resolve, or our commitment to the country's unity and territorial integrity," it said.
"The Prime Minister again drew the President's attention to Pakistan's commitment to ending cross-border terrorism and said we continue to be disturbed and dismayed at indications of the external linkages of terrorist groups with the October 29 bombing, and said India expects Pakistan to act against terrorism directed at India."
Although Singh referred to "external linkages" he did not name Pakistan, but Indian foreign ministry officials said he was referring to Pakistan.
Pakistan's Foreign Ministry said Islamabad was ready to extend full co-operation in the investigation.
"The President has said we are ready to cooperate in the investigations," ministry spokeswoman Tasnim Aslam said. "But evidence has to be shared with us."
"In the absence of that it will be just a claim. While pointing fingers on any Pakistan entity, they should also share evidence with us."
An obscure Kashmiri militant group, Islami Inqilabi Mahaz (the Islamic Revolutionary Front) claimed responsibility for the attacks.
Indian analysts and police said the Mahaz was linked to Lashkar-e-Taiba that was banned by Pakistan in 2002.
A Lashkar-e-Taiba spokesman said the group was not involved in the attacks and had no links to the Mahaz.