The Indian government today admitted that intelligence and security mistakes were made before last week's terrorist strikes on Mumbai.

The admission comes as public anger grows at the authorities' lax handling of the attacks, which killed nearly 200 people.

The newly appointed Home Minister, Palaniappan Chidambaram, said: "Ultimately there have been some lapses. These are being looked into and I will do my utmost ... to overcome the causes of these lapses and try to improve the effectiveness of the security system.

"What happened in Mumbai must be the trigger for a fundamental change of our attitude towards terrorism and combating terrorism. Neither the state governmental authorities nor the citizens can go back to business as usual."

As he was speaking, India's major airports were on high alert after officials said that credible intelligence had been unearthed that indicated a plot to hijack a plane in an attack that could have resembled those mounted in New York in 2001.

There has been a public outcry in India in the wake of the deadliest terrorist attack to hit the country in 15 years. Last year India trailed only Iraq in terms of the number of people killed in terrorist attacks and there have been at least 11 serious strikes across the country in the past 12 months. Now, many Indians are angry that numerous reports warning of a terrorist strike on the country's financial capital were not acted upon.

There is also fury that well-equipped troops took at least eight hours to make a two-hour flight to Mumbai from their base near Delhi as a plane was not immediately available. Even the group of elite marine commandoes based in Mumbai did not arrive at the Taj Mahal and Oberoi hotels until 1am, about three and a half hours after the first shots were fired, by which time gunmen had trapped hundreds of guests.

In the preceding hours, Mumbai's security was in the hands of an under-equipped police force which found itself outgunned and overwhelmed by ten heavily-armed gunmen wielding AK-47s and grenades.

Experts say the safety of the city had effectively been placed in the hands of the anti-terror squad of the Mumbai police - a unit that has just 200 staff and is responsible for a city with a population of 18 million.

The faith of Mumbai's residents in their security forces, already sorely tested, was given another severe blow this week, when a bag containing 8kg of explosives was found at Chhatrapati Shivaji Terminus, Mumbai's main train station and one of the world's busiest.

Two gunmen killed 56 people at the terminus last Wednesday. It is thought the explosives, which were found with the bags of passengers who fled the station that night, had lain there undiscovered since the attacks.

Yesterday, it emerged that a private company that supplied explosives sniffer dogs to one of Bombay's rail operators had withdrawn its services because a bill of about £2,000 had not been paid. A Western Railway official refused to comment on the matter.

There have also been reports that the boat possibly used by the terrorists, who arrived in Mumbai by sea, was spotted off the coast of Gujarat but that at an alert to check the vessel was ignored.

This week thousands of protesters gathered at the Gateway of India, close to the Taj Mahal Palace, one of the two luxury hotels attacked last Wednesday. "Our politicians are thieves" was one of the slogans being shouted. There were also anti-Pakistan chants.

Mr Chidambaram took over as India's home minister on Sunday, the day after the attacks finally ended, replacing Shivraj Patil, who took "moral responsibility" for the assault and resigned.

Mr Chidambaram did not reveal any details of the investigation that left 172 people dead.

"All 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, if parliament is in session at that time," he said.

The minister also repeated India's claim that "this particular crime was committed by terrorists who came from outside the country."

He said: "There is ample evidence to show that the source of the terrorist attack was clearly linked to organisations which have in the past be identified as being behind terrorist attacks in India.

"There are one or two countries which have broadly confirmed our preliminary conclusions ... At this stage of the investigation it would be inappropriate for me to name any organisation or any entity."

Mr Chidambaram's words are likely to be interpreted as pointing towards Pakistan. Several Indian officials have claimed that the gunmen were all from Pakistan and linked to the Lashkar-e-Taiba militant group, which was formed to free Kashmir from Indian rule.

Mr Chidambaram described the attacks as a "horrific tragedy" and pledged that the government would do all it could to investigate what happened.

"The government is determined to take the investigation to its logical conclusion and punish the guilty," he said.

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