FACTBOX - Main suspects behind blasts in India's Assam

(Reuters) - Eleven bomb blasts in quick succession ripped through the main city of India's troubled northeastern Assam state and three other towns Thursday, killing 77 people and wounding more than 320, police said.

Here are some of the main groups suspected to be behind the attacks:

* ULFA

The United Liberation Front of Asom (ULFA) is Assam's major separatist group that has been fighting since 1979. It accuses New Delhi of plundering the state's mineral resources and giving back nothing in return. ULFA is often blamed for attacks in Assam, but the group has denied responsibility for the Oct 30 blasts.

* HuJI

Harkat-ul-Jehad al Islami (HuJI) is a Bangladeshi militant Islamist group that has often been suspected of attacks on Indian cities.

HuJI has been linked to ULFA. Assam has a long-simmering conflict between its indigenous population and Bangladeshi immigrants, many of them illegal. Mainly Hindu tribesmen fear being overrun by Muslims, who make up 40 percent of the state.

Indian police say HuJI is also connected to the little-known Indian Mujahideen group, which claimed responsibility for a series of bomb attacks in Indian cities in 2008. HuJI was blamed for the 2004 bombing of a political rally addressed by former prime minister Sheikh Hasina and an attack on Bangladeshi born British High Commissioner Anwar Chowdhury.

* Jamaat-ul-Mujahideen