Police raided the home of an American citizen in Mumbai, India's financial capital, and seized a computer from which an e-mail claiming responsibility for bombings that killed 45 people in western India was believed to have been sent, officials said Monday.

The 48-year-old American has not been detained and is not currently a suspect, police said.

Anti-terror police also arrested an underworld figure in Ahmadabad with apparent ties to a banned Muslim group and were determining whether he had any connection to the weekend attack in the city, said deputy police chief Ashish Bhatia.

At least 16 bombs tore through Ahmadabad around dusk Saturday, killing 45 people and wounding 161 others, said state Health Minister Jaynarayan Vyas. It was the second series of blasts in India in two days.

An obscure Islamic militant group took credit for the Ahmadabad attack.

"In the name of Allah the Indian Mujahideen strike again! Do whatever you can, within 5 minutes from now, feel the terror of Death!" said an e-mail from the group sent to several Indian television stations minutes before the blasts began.

The e-mail's subject line said "Await 5 minutes for the revenge of Gujarat," an apparent reference to 2002 riots in the western state that left 1,000 people, mostly Muslims, dead. The historic city of Ahmadabad was the scene of much of the 2002 violence.

Saturday's e-mail, sent from a Yahoo account and written in English, was made available to the AP by CNN-IBN, one of the TV stations that received the warning.

Late Sunday, police raided a home in a Mumbai suburb rented by the U.S. citizen, believing the e-mail may have been sent from a computer there. Mumbai police Chief Hassan Gafoor said police confiscated a computer and were analyzing the hard drive.

Police said it is likely the e-mail was forwarded and may not have originated from the computer of the U.S. citizen.

Kirit Sonawane, a police officer involved in the raid, said the American was a resident of California, but gave no other details. "We have not registered any offense. The mail may have been forwarded from his computer," he said.

A.N. Roy, the state police chief of Maharashtra, of which Mumbai is the capital, said no arrests had been made. "He is not yet a suspect," Roy said of the U.S. national, declining to give any further details about the e-mail.

"We have not yet come to any conclusions about that yet. Inquiries are on," Roy said.

In Ahmadabad, police arrested a man identified as Abdul Haleem who was suspected of involvement in the plot, Bhatia said. Haleem had ties to the banned Students' Islamic Movement of India and groups involved in the 2002 riots, he said.

On Monday, an Ahmadabad court ordered Haleem held for 14 days.

The group that claimed responsibility for the Ahmadabad attacks was unknown before May, when it said it was behind a series of bombings in Jaipur, also in western India, that killed 61 people.

In the e-mail, the group did not mention the bombings that killed two people a day earlier in Bangalore, and it was not clear if the attacks were connected.

The Saturday bombs went off in two separate spates. The first, near a busy market, left some of the dead sprawled beside stands piled high with fruit, next to twisted bicycles. The second group of blasts went off near a hospital.

On Monday Prime Minister Manmohan Singh and the leader of India's governing Congress party, Sonia Gandhi, arrived in Ahmadabad and visited wounded survivors at the hospital that was also the site of one of Saturday's blasts.

India has been hit repeatedly by bombings in recent years. Nearly all have been blamed on Islamic militants who allegedly want to provoke violence between India's Hindu majority and Muslim minority, although officials rarely offer hard evidence implicating a specific group.