MUMBAI (Reuters) - Militants armed with automatic weapons and grenades attacked luxury hotels, hospitals and a famous tourist cafe in India’s commercial capital Mumbai late on Wednesday, killing at least 101 people.

* WHO IS BEHIND THE ATTACKS?

The attacks were claimed by a previously unknown group calling itself the Deccan Mujahideen in an e-mail to news organizations. Deccan is an area of southern India.

But it is not clear if the claim is genuine, and analysts say the bombings are almost certainly the work of a different group.

The most likely perpetrators, they say, are either the Indian Mujahideen or Lashkar-e-Taiba.

* WHO ARE LASHKAR-E-TAIBA?

Lashkar-e-Taiba is one of the largest Islamic militant groups in South Asia, based in Pakistan and fighting Indian rule in Kashmir. Security analysts say it is a well-funded and highly organized group that sympathizes with al Qaeda.

Lashkar-e-Taiba denied being behind the Mumbai attacks and said it condemned them.

The group was blamed for bomb attacks on markets in New Delhi that killed more than 60 people in 2005, as well as an assault on India’s parliament in 2001 that brought India and Pakistan to the brink of a fourth war.

* WHO ARE THE INDIAN MUJAHIDEEN?

Indian police say the Indian Mujahideen is an offshoot of the banned Students’ Islamic Movement of India (SIMI), but that local Muslims appear to have been given training and backing from militant groups in neighboring Pakistan and Bangladesh.

SIMI has been blamed by police for almost every major bomb attack in India, including explosions on commuter trains in Mumbai two years ago that killed 187 people.

Police said the Indian Mujahideen may also include former members of Bangladeshi militant group Harkat-ul-Jihad al Islami.

The group first emerged during a wave of bombings in the northern state of Uttar Pradesh in November 2007, sending an e-mail to media outlets just before some of the bombs exploded.

They have since claimed responsibility for multiple bomb attacks in Jaipur, Bangalore, Ahmedabad and New Delhi.

* WHO DOES INDIA BLAME?

Indian Prime Minister Manmohan Singh said the attacks were probably plotted by a group based in a neighboring country.

But Indian governments often blame neighboring Pakistan or sometimes Bangladesh for supporting or harboring militant groups which have launched attacks on Indian soil.

* WHAT CAN BE INFERRED FROM THE ATTACKERS’ TACTICS?

The Mumbai attacks were unusual in that they involved coordinated attacks by gunmen on multiple targets, hostages were taken, and foreigners were specifically targeted.

Several analysts say these tactics point to Lashkar-e-Taiba as being involved. The attacks on symbolic targets designed to gather maximum publicity, and the specific targeting, point to a group following al Qaeda ideology and tactics.

The attacks also show a considerable degree of sophistication, another factor pointing to an experienced group like Lashkar-e-Taiba.

The Indian Mujahideen have also surprised police with the sophistication of their attacks, however, although until now these have always been bomb attacks on Indian targets.

In May, the Indian Mujahideen made a specific threat to attack tourist sites in India unless the government stopped supporting the United States in the international arena.

The threat was made in an e-mail claiming responsibility for bomb attacks that killed 63 people in the tourist city of Jaipur. The mail declared “open war against India” and included the serial number of a bicycle used in one of the bombings.

* WHAT CAN BE INFERRED FROM THEIR DEMANDS?

A man speaking Urdu with a Kashmiri accent phoned an Indian TV station, offering talks with the government and accusing the Indian army of killing Muslims in Kashmir. This suggests the attackers are involved with a Kashmiri group like Lashkar-e-Taiba.

The demands of the Indian Mujahideen -- like their targets -- have always tended to be much more domestic. The group issued an e-mail threat in September to attack Mumbai but directed its anger at the Mumbai police anti-terrorist squad, accusing them of harassing Muslims.

“If this is the degree your arrogance has reached, and if you think that by these stunts you can scare us, then let the Indian Mujahideen warn all the people of Mumbai that whatever deadly attacks Mumbaikars will face in future, their responsibility would lie with the Mumbai ATS and their guardians,” it said.