Police in Bombay have been searching for more bombs after an explosion in a marketplace on Monday injured about 30 people, eight critically.

The search came as Prime Minister Atal Behari Vajpayee visited the city on Tuesday.

The entire city is on high alert. We are stopping vehicles and conducting checks Police commissioner RS Sharma

The homemade explosive went off in a crowded marketplace in the Ville Parle suburb at about 2030 (1500 GMT) on Monday.

Police believe the bomb, which sent nails and shrapnel flying, might have been planted on a booby-trapped bicycle.

Trails of blood could be seen all around the area, which was cordoned off by police.

Elite team

Mr Vajpayee visited Bombay on Tuesday to inaugurate a fair.

About 30 were hurt, eight critically

Bombay Police Commissioner RS Sharma said: "The entire city is on high alert. We are stopping vehicles and conducting checks. We have also started searching local trains as a precaution."

Bombay's joint commissioner of police, Javed Ahmed, said a special team of investigators from the elite National Security Guard was to examine the scene.

Locals said casualties would probably have been much higher it the blast had occurred on another day, as the marketplace is closed on Mondays.

A second crude explosive device was found 30 metres from the scene of the first blast.

It exploded four hours after the first, before police had had a chance to defuse it.

No one was injured.

December attacks

Bombay, also known as Mumbai, has been hit by two recent explosions.

In December, two people were killed and 31 wounded when an explosion ripped off the rear of a bus.

Several days later 23 were injured in a blast at a food court housing a McDonald's outlet.

No one has claimed responsibility for the attacks.