Indian Prime Minister Manmohan Singh (search) told Pakistan's president there were indications of a foreign link to the bombings that struck two New Delhi markets, and he reminded the Pakistani leader of his country's promise to fight terrorism, an official said.
In Pakistan, President Gen. Pervez Musharraf (search) condemned Saturday's bombings that killed 59 people in India as "a dastardly terrorist attack," and said Pakistan would fully cooperate in any investigation.
Pakistan-based Islamic militants have been suspected in the bombings, but Indian officials appeared hesitant to immediately place blame. Indian analysts and newspapers have pointed the finger at the Pakistani-based groups fighting to wrest Kashmir (search) from India.
Musharraf called Singh to express his condolences, and Singh told him that the bombing investigation indicated "external linkages of terrorist groups" with the attacks, said Sanjaya Baru, a spokesman for the Indian leader.
At a news conference in this garrison city near the capital of Islamabad, Musharraf said: "Pakistan stands with India."
He also said the deadly earthquake that devastated the Kashmir region divided between Pakistan and India was an opportunity for the countries to advance negotiations over their conflicting claims to the Himalayan region.
"I think this is an opportunity which we should utilize for moving ahead" on a final solution for Kashmir, he said, repeating his willingness to demilitarize the region.
Pakistan and India on Sunday agreed to open five crossing points in the heavily militarized border to speed relief to quake victims.
New Delhi slowly crept back to life Monday after the bombings, but the two markets targeted in the attacks were unusually quiet on what would have normally been one of the busiest shopping days of the year.
A little-known group that police say has ties to Kashmiri militants claimed responsibility Sunday for the blasts, which took place as shoppers prepared for a major Hindu festival. A third bomb that targeted a bus did not kill anyone but injured nine people.
On Sunday, a man called a news agency in Indian Kashmir claiming the militant group Islamic Inquilab Mahaz (search), or Front for Islamic Uprising, had staged the deadly bombings which also injured 210 people.
New Delhi's deputy police chief, Karnail Singh, said the group has ties with the Pakistan-based Lashkar-e-Tayyaba (search), the most feared of the dozens of Kashmiri militant groups.
The caller, who identified himself as Ahmed Yaar Ghaznavi, said the bombings were "meant as a rebuff to the claims of Indian security groups" that militants had been wiped out by security crackdowns and the massive quake that devastated the insurgents' heartland in the mountains of Kashmir.
Police in Indian Kashmir said intelligence agencies were not familiar with the caller's name and the government refused to comment on the claim of responsibility.
On Monday, wary residents of the capital returned to work after the bombings struck during the city's biggest shopping weekend of the year, ahead of the Hindu festival of lights, Diwali (search).
Thousands of shoppers fled the markets immediately after the bombings. At the Sorojini Nagar (search) market, one of the two targeted in the attacks, crowds were thin Monday. Most people had come to see the scene of the blast, not shop.
"Normally on this day, the day before Diwali, you wont get any place in my shop to stand," said Harsh Goplan, who runs a clothing store in the market, where 43 people were killed.
"The fact that I am here taking to you, talking to other journalists says it all — that there are no customers today," he said.
At the market and throughout New Delhi, security was tight. Dozens of police in uniform and plainclothers patrolled the streets, most armed with assault weapons.
Sarojini Nagar — considered the city's favorite shopping hub — was busier on Sunday, with some shoppers saying they had come to defy the attackers.
"We came here to express solidarity," said Shibani Mahalanobis, a 66-year-old grandmother who has shopped in the market for 45 years.
Polish diplomat Jindrick Hacker, 37, was at the market Sunday to buy a shoe rack. He compared the attack to the London transit bombings in July, and said he had left his daughters at home rather than take them shopping as planned.
"There is some fear. To not fear will be stupid," he said.
Authorities said they already had gathered useful clues about the bombings. Police said they were questioning "numerous" people.
Police were looking for a man in his 20s who refused to buy a ticket on a bus and got off, leaving behind a large black bag, said Singh, the deputy police chief. The bag caused a panic onboard, prompting the driver and conductor to throw it from the bus just as it exploded, injuring them both and seven others.
The Hindu nationalist Bharatiya Janata Party (search) — India's main opposition party — has urged the government to review what it called its "soft border" policy with Pakistan.
Under the deal agreed Sunday, people will be able to cross the frontier in Kashmir at five points starting Nov. 7 to help get food, shelter and medicine to victims of the quake, which killed about 80,000 people and left 3 million homeless, most in Pakistan.
India and Pakistan have fought three wars since the subcontinent was partitioned at independence from Britain in 1947, two over Kashmir.