Q+A: Who could be behind the Mumbai attacks and why?

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?