With the authorities suspecting a militant Islamic group to be behind the attack, crack police teams maintained night-long vigils and set up check points at vulnerable areas of the western city, a police spokesperson said.

No arrests as yet

However, by Friday morning no arrests had been made in connection with the bombing, which rocked a packed commuter train as it pulled into Bombay's Mulund suburban station around 8.45pm local time on Thursday.

"The toll is now 11, with around 65 people injured," said inspector Jadhav of the Bombay police control centre, who uses just one name.

Of the fatalities, three were females and the rest males, he said.

Witnesses had earlier said most of the victims were women as the bomb was planted in a women's only carriage.

Bomb exploded on edge of women's carriage

However, Jadhav said it now appeared the powerful bomb exploded on the edge of the women's carriage and that an adjoining coach also bore some of the brunt.

Police said they suspected the Students' Islamic Movement of India (SIMI) could be behind the attack, but did not rule out the hand of other militant groups.

Deputy chief minister of the western Indian state of Maharashtra, Chhagan Bhujbal, blamed "terrorists" for the bombing.

"These people are everywhere and Bombay is no exception. What we as government and the people have to do is remain continuously alert. We are searching for clues that could lead us to the culprits," he said.

Commuters panicked

The blast panicked commuters, most of them office workers on their way home. Briefcases, handbags and paper files fluttered down on platform number three at Mulund as office workers reinforced by fire department rescuers and rail staff rushed the injured to nearby hospitals.

The impact was so powerful it blew a gaping hole in the metal structure and left seats a mess of twisted metal.

Doctors said most of the victims suffered injuries from the waist down.

"Some also have chest injuries but most of the injured brought in here have injuries to their legs and stomachs," said physician S.M. Goswami, principal of Mulund Medical College and Hospital.

"But also there are some with head injuries," he said.

Blast similar to earlier attack

Thursday's attack came a day after the 10th anniversary of a string of bomb blasts that killed or maimed more than 300 people in Bombay. But police were reluctant to link Thursday's bombing to the anniversary, saying the hand of SIMI appeared to be behind the attack.

"The pattern of the blast is very similar to the one which happened in the passenger bus," Javed said, referring to a blast on a Bombay bus on December 2 which left two people dead and 27 injured, and for which police blamed SIMI.

Just days after the December 2 bus bombing, a blast occurred in a McDonald's fast food outlet, injuring 23.

In January, 30 people were wounded when a crude bomb planted in a bicycle exploded in a crowded street in a Bombay suburb.

Joint police commissioner Shridhar Wagal said it appeared the attacks were linked.

"Prima facie the train bomb appears to be very similar to the earlier ones, especially the one used in the passenger bus," he said.

"But the intensity of this bomb is more than the earlier ones. I would say it was of medium to high intensity as virtually the entire right side of the carriage and part of the top was blown away. leaving large gaping holes."

No one has yet claimed responsibility for the blasts.