Last month's bus bomb killed three and sparked a strike

The spate of attacks led the city authorites to announce the setting up of an anti-terrorist squad recently, modelled on the Indian army's paramilitary commando forces, the National Security Guard.

Police say the unit, armed with assault rifles and enhanced communication devices, is needed because Bombay's commercial significance makes it a key target.

Last December a bomb blew off the rear of a bus killing two people and wounding 26.

In March, a bomb exploded on a rush-hour train, killing 11 people and injuring 75.

And last month, another explosion on a bus killed three and injured 42.

Monday's blast came as the Ayodhya report was filed

No one has claimed responsibility for the attacks.

Right-wing Hindu parties, including Prime Minister Atal Behari Vajpayee's Bharatiya Janata Party have pointed the finger at Pakistani-based militants for previous bombings.

This time, as India and Pakistan enjoy a thaw in relations, the government in Delhi has not rushed to criticise Islamabad.

And Pakistan has moved swiftly to condemn Monday's blasts.

Bombay police named the Islamic militant group, Lashkar-e-Toiba, as being possibly behind the July bus attack.

But no substantial evidence has been produced to back up the accusations.

Lashkar-e-Toiba is one of the two groups Delhi blames for an attack on the Indian parliament in December 2001 which sparked a diplomatic crisis with Pakistan that has only thawed this year.

Monday's attacks came at a particularly sensitive time.

Bombay suffered badly following the nationwide riots that were sparked by the destruction of a mosque at Ayodhya in 1992 in which more than 2,000 people died.

Towards the end of the riots a series of bomb blasts in the city killed more than 200 people. Those blasts have been widely blamed on underworld criminals.

A court on Monday released a report on an excavation at Ayodhya aimed at clarifying whether Hindu hardliners are justified in demanding that a Hindu temple be built at the Ayodhya site.

Already both Hindu and Muslim activists have drawn very different conclusions about the findings of the report.

That the release of the report has coincided with the bomb blasts has been widely noted. But as yet, there is no proof of any connection.