With national elections just months away, Patil said he accepted "moral responsibility" for failing to prevent the attacks.
'Elements in Pakistan'
As the city began to mourn its dead and security officials stepped up their investigation, the Indian government was continuing to link those behind the attacks to neighbouring Pakistan, Al Jazeera's Sohail Rahman said from Mumbai.
Pranab Mukherjee, India's foreign minister, said "according to preliminary information, some elements in Pakistan are responsible".
With the suspicion that elements in Pakistan were involved, the Indian government is considering suspending peace talks with its neighbour, the Press Trust of India (PTI) reported.
"There is a view in the government that India should suspend the peace process and composite dialogue to show that it is not going to take lightly the deadly carnage in Mumbai," the official Indian news agency quoted an unnamed official as saying.
Although the Indian government has confirmed moving troops to the Line of Control at the quasi border with Pakistan in Kashmir, it maintains that the painfully negotiated ceasefire with Islamabad there is still in place, our correspondent said.
Kanwal Sibal, a former Indian foreign secretary, told Al Jazeera: "We have been put in an extremely difficult situation where, on the one hand we need to respond - we must respond, otherwise we lay ourselves open to more such attacks in the future.
"On the other hand, we also want the democratic government in Pakistan to survive and we do not want the armed forces to come back."
|The commando operation at the Jewish centre
was criticised as slow [Reuters]
But Islamabad has denied any links to the attacks and called on New Delhi to share evidence.
Assad Durrani, a former head of Pakistan's Inter-Services Intelligence (ISI), told Al Jazeera: "I heard that India would be prepared to share their intelligence with Pakistan, so that is already a positive move, because that has been a problem in the past.
"And, in most cases, if I recall correctly, it turned out that either they did not have any good proof or someone else was responsible."
Earlier Shah Mahmood Qureshi, Pakistan's foreign minister, said: "Our hands are clean, we have nothing to hide and nothing to be ashamed of because this government feels that good neighbourly relations with India are in the interests of Pakistan."
The only attacker captured alive after the 60-hour siege said he belonged to a Pakistani armed group with links to the disputed Himalayan region of Kashmir, a senior police officer said on Sunday.
Joint Police Commissioner Rakesh Maria said Ajmal Qasab told police he was trained at a Lashkar-e-Taiba camp in Pakistan, the group he said was "behind the terrorist acts" in Mumbai.
A US counterterrorism official had said some "signatures of the attack" were consistent with Lashkar and Jaish-e-Mohammed, another group that has operated in Kashmir, both accused of having links to al-Qaeda.
Security forces criticised
India's security forces have also come under heavy fire for being unprepared and ill-equipped to handle the Mumbai attacks.
Although Manmohan Singh, the Indian prime minister, promised to boost maritime and air security and consider a new federal investigative agency, some analysts expressed doubts that there would be any fundamental change.
|Patil said he took "moral responsibility" for the attacks [EPA]
"These guys could do it next week again in Mumbai and our responses would be exactly the same," said Ajai Sahni, head of the New Delhi-based Institute for Conflict Management who has close ties to India's police and intelligence agencies.
He said the 10-hour delayed response by commandos based outside of New Delhi gave the gunmen time to consolidate control of two luxury hotels and a Jewish centre in Mumbai.
Sahni said not only were the local police poorly trained, even the commandos lacked proper equipment such as night-vision goggles and thermal sensors that could have helped better locate the attackers.
In the first of a series of attacks, two young men armed with assault rifles had managed to spray bullets in the city's crowded main train station despite more than 60 patrolling police officers.
"The way Mumbai police handled the situation, they were not combat-ready," Jimmy Katrak, a security consultant, said. "You don't need the Indian army to neutralise eight to nine people."
Bapu Thombre, the assistant commissioner with the Mumbai railway police, said policemen who were armed mainly with batons or World War I-era rifles "are not trained to respond to major attacks".
Indian commandos were also severely criticised for the slow response to the hostage situation at the Jewish centre in Mumbai.
Assaf Hefetz, a former Israeli police commissioner, said the commandos should have swarmed the building in a massive, co-ordinated attack that would have overwhelmed the gunmen and ended the standoff in seconds.
The slowness of the operation he said made it appear as if the commandos' main goal was to stay alive.
"You have to take the chance and the danger that your people can be hurt and some of them will be killed, but do it much faster and ensure the operation will be finished [quickly]," said Hefetz, who created the Israeli police anti-terror unit 30 years ago.
But JK Dutt, the director-general of the commando unit, defended their tactics.
"We have conducted the operation in the way we are trained and in the way we like to do it," he said.
Meanwhile Condoleezza Rice, the US secretary of state, is scheduled to visit the Indian capital this week as a "further demonstration" of US solidarity with India and to "work together to hold these extremists accountable", the White House said on Sunday.