India - and Mumbai - are no stranger to terrorism but the attacks on multiple targets in the city mark a significant step change. Previous attacks involved the leaving of explosives in public places like markets or on trains. These could be devastating in terms of the loss of life, with nearly 200 killed in 2006. But the latest attacks are different in terms of both method and scale, with teams of well-armed men involved in synchronised attacks - the gunmen were also clearly prepared to die in their attacks. Another major difference is the targeting of restaurants and hotels used by westerners and the apparent singling out of those with British and American passports. This points to either a major shift in strategy by an existing group or the influence or direction of outside parties, perhaps even al-Qaeda, whose style of attacks this mimics. The growing tide of attacks raises major problems for the Indian authorities   A group calling itself the Deccan Mujahideen has claimed responsibility for the attacks but little is known of it. The men were of South Asian appearance and reportedly spoke Hindi, indicating they originated in India. Attacks over recent years have seen a variety of different groups named, particularly the Indian Mujahideen who had apparently threatened to attack Mumbai in September, claiming that Muslims had been harassed. The authorities have often pointed the finger at the Students' Islamic Movement of India, believing that other groups like the Indian Mujahideen are a front for this banned organisation. Some attacks have also been blamed on Lashkar-e-Toiba, which India says is backed by Pakistan's intelligence agency the ISI.

India's Prime Minister Manmohan Singh has vowed to take "whatever measures are necessary" to track down those responsible for the Mumbai attacks.

He said the perpetrators were based "outside the country" and India would not tolerate "neighbours" who provide a haven to militants targeting it.

Gunmen targeted at least seven sites across Mumbai late on Wednesday, killing 101 people and injuring 300.

Some 200 people are still reportedly trapped inside one hotel, the Oberoi.

Police earlier said hostages had been freed from another luxury hotel, the Taj Mahal Palace, but explosions and gunfire are still being heard by witnesses outside.

Meanwhile, a stand-off between Indian troops and gunmen continues at a Jewish centre in the city, where an Israeli rabbi and his family were reportedly taken hostage.

'Create havoc'

In a televised address, Mr Singh said the government "will take whatever measures are necessary to ensure the safety and security of our citizens."

He described the attacks as "well-planned and well-orchestrated... intended to create a sense of panic by choosing high profile targets and indiscriminately killing foreigners."

MUMBAI ATTACKS

The perpetrators were "based outside the country", he said, adding that they "had come with single-minded determination to create havoc in the commercial capital of the country".

India has complained in the past that attacks on its soil have been carried out by groups based in Pakistan, although relations between the two countries have improved in recent years and Pakistani leaders were swift to condemn the latest attacks.

Claim of responsibility

Gunmen, using grenades and automatic weapons, targeted at least seven sites including the city's main commuter train station, a hospital and a restaurant popular with tourists late on Wednesday night.

Police say 14 police officers, 81 Indian nationals and six foreigners have been killed. A Japanese businessman and an Italian national were confirmed to be among the dead.

Four suspected terrorists have also been killed and nine arrested, they add.

State police chief AN Roy earlier told local television that hostages held by the gunmen at the Taj Mahal Palace hotel - one of Mumbai's most famous hotels - had been freed.

Witnesses said civilians could be seen running from the hotel, some with suitcases. Ambulances were also reported to be arriving.

But the BBC's Mark Dummett, outside the Taj Mahal, says the situation has since become very confused, with the sounds of explosions and gunfire being heard from within the hotel, suggesting the siege is not yet over.

Earlier in the day, Indian commandos had been seen entering the hotels but there was little detail on the operation.

Meanwhile, the bosses of the Oberoi hotel across town say some 200 guests are still trapped in their rooms.

Earlier eyewitness reports from the hotels suggested the attackers were singling out British and American passport holders.

If the reports are true, our security correspondent Frank Gardner says it implies an Islamist motive - attacks inspired or co-ordinated by al-Qaeda.

A claim of responsibility has been made by a previously unknown group calling itself the Deccan Mujahideen. Our correspondent says it could be a hoax or assumed name for another group.