Those attacks were blamed on Dawood Ibrahim, an Indian Muslim gangster with alleged links to al-Qa'ida.
Although Indian officials last night said it was too early to say who was behind the Delhi blasts, initial suspicions are bound to fall at the door of Islamist extremists. An alert was recently issued in India after a tip-off from the Americans that Islamic militants were planning attacks on US interests here, possibly using suicide car bombs.
The targeting of shoppers ahead of the Hindu festival of Diwali certainly seems to point to Islamist extremists. But people were also shopping ahead of the Muslim festival of Eid al-Fitr, which marks the end of Ramadan, and yesterday's bus bombing was in a mainly Muslim area of Delhi.
India has a history of attacks by Islamist extremists. Hindu-Muslim relations have been poor since Hindu hard-liners demolished a 16th-century mosque in 1992 in Ayodhya. More than 3,000 people died in religious riots that followed, and the Bombay bombings were said to be an act of retaliation.
Then there is Kashmir. The separatist movement fighting Indian rule in this disputed land was started by non-religious Kashmiri nationalists, but it was swiftly hijacked by Islamist extremists, backed by Pakistan.
The older generation of separatists has since forsworn violence. But Islamist militants still regularly commit attacks in Indian-held Kashmir, and India accused the militant Lashkar-e Toiba group, based in Pakistan, of a 2001 attack on parliament in Delhi.
India and Pakistan came close to nuclear war after India accused Pakistani intelligence of being behind the attack.
But Islamist militants are not the only possible culprits for the Delhi blasts. India is fighting a range of home-grown militant groups, including small separatist outfits. Among those who may have the capability for such an attack are the Maoist revolutionary Naxalites, though they have never committed an outrage on these lines before.
Two cinema bombings months ago in which one person died were blamed on Sikh extremists. In the 1980s, Sikh militants were behind blasts in Delhi, and the notorious bombing of an Air India flight from Canada to India in 1985.
But the Sikh insurgency has long ended, and the cinema bombings were said to be the work of a fringe group.Reuse content