Many in India are describing the attacks as India's 9/11
India's new home minister has admitted that there were security lapses in last week's militant attacks on Mumbai.
Palaniappan Chidambaram said the lapses were being "looked into" and their "causes would be addressed soon".
Officials have now revised the death toll - they say 172 people died, including nine gunmen, in the attack on multiple targets in the city.
India has blamed Pakistan-based militants for the attacks. Islamabad denies any role.
On Friday Indian Prime Minister Manmohan Singh said Indians were "angry as never before" over the attacks.
The Indian government has faced growing criticism at home over its handling of the attacks.
Mr Chidambaram took over as home minister on Monday after his predecessor Shivraj Patil was forced to quit amid media and opposition criticism that he was taking a "soft approach on terror".
"I would be less than truthful if I said there were no lapses," Mr Chidambaram told reporters in Mumbai.
"These are being looked into. We will address the causes that led to the lapses."
Mr Chidambaram refused to give any details of the investigation into the attacks.
"Work is under way. A lot of evidence has been gathered. Many aspects are being checked... and when the full picture is drawn up I expect to be able to make a statement in parliament," he said.
Security was enhanced across Mumbai after the attacks
When asked about the possible involvement of Pakistan's spy agency, the Inter-Services Intelligence, Mr Chidambaram said: "There is ample evidence to show the source of the attacks was clearly linked to organisations which have in the past been identified as behind terrorist attacks in India."
US media said this week that Washington had warned India in October that Mumbai could be targeted by militants arriving by sea.
The home minister said the death toll now stood at 172 which included 163 civilians and members of the security forces, and nine militants.
Mr Chidambaram said 18 security force officers were killed, among them the head of Mumbai's anti-terrorism squad, Hemant Karkare.
Many of the 293 people who were injured were still undergoing treatment, he said.
Meanwhile, Russian President Dmitry Medvedev - who is on a visit to India - offered to help India fight terrorism and investigate the attacks in Mumbai.
"Terrorism is a common enemy. We are ready to help India in fighting this menace," India's national channel Doordarshan quoted him as saying.
Azam Amir Qasab was the sole militant captured alive
Following talks with Mr Medvedev, Mr Singh said it was "the obligation of all concerned that perpetrators of this horrible crime are brought to book".
He added: "The people of India have felt a sense of hurt and anger as never before due to the Mumbai terror strikes."
On Thursday, India said it had decided to put "on hold" all official initiatives to boost trade with Pakistan.
"Quite clearly, the environment being what it is now, we have put everything on hold," the Indian Express newspaper quoted Minister of State for Commerce and Power Jairam Ramesh as saying.
"The way forward depends on [Pakistan's] response. If it is positive, we can go back to doing all that both sides had proposed on improving trade," he said.
Last week's attacks shocked the country, with many describing it as India's 9/11.
Three major airports in India are on heightened alert after a threat of attacks by the Deccan Mujahideen, the previously unknown militant group who claimed responsibility for last week's Mumbai attacks.
India has blamed Pakistan-based banned group Lashkar-e-Toiba for the attacks. It denies involvement.
US Secretary of State Condoleezza Rice visited both India and Pakistan this week to try to ease tensions.
In Islamabad, Pakistani President Asif Ali Zardari vowed to take "strong action" against any elements in his country that were involved in Mumbai attacks.
"Pakistan is determined to ensure that its territory is not used for any act of terrorism," he said.
Ms Rice demanded "a robust response" from Pakistan but warned India should not take actions that would provoke "unintended consequences".