India blasts: Death toll reaches 45

India's major cities are on high alert, with fears of more attacks after two days of bombings that hit a religiously sensitive western city and a southern IT hub.

Most of the 16 blasts were in the city's Muslim old quarter, which has been the scene of clashes between Hindus and Muslims in the past. Sectarian violence in 2002 left hundreds dead.

A little-known group called the "Indian Mujahideen" claimed responsibility for the Ahmedabad attack. The group said it carried out bomb attacks that killed 63 people in the western city of Jaipur in May.

Two more unexploded bombs were found in the city of Surat, one of the world's biggest diamond-polishing centres in Gujarat state, police said.

The government has called for calm as police used loudspeakers and distributed leaflets in crowded market places, warning people to watch out for unclaimed baggage and suspicious objects. Police guarded Hindu temples in the eastern city of Kolkata.

There were fears the blasts could set off fighting between religious groups.

"This has been done by some terrorist group which wants to destabilise the country," the central government's junior home minister Shriprakash Jaiswal said.

A number of Indian cities have been hit by serial blasts in recent months which have been blamed on Islamic militants, including Bangalore on Friday when two died.

Most of the blasts took place in the narrow lanes of the older part of Ahmadabad, which is crowded with tightly packed homes and small businesses.

Distraught relatives of the wounded crowded the city's hospitals and television channels showed video footage of police officers and sniffer dogs scouring the areas that were hit.

There were images of a bus with shattered windows, destroyed roadside stalls, twisted bicycles and charred vehicles.

Prithviraj Chavan, a junior minister in the prime minister's office, called the explosions "deplorable" and said they were set off by people "bent upon creating a communal divide in the country" — language officials usually use when blaming Islamic militants believed to be behind bombings that have repeatedly hit India's cities in recent years.

"Anti-national elements have been trying to create panic among the people of our country. Today's blasts seem to be part of the same strategy," federal Home Minister Shivraj Patil told reporters in New Delhi.

The latest attacks came a day after seven synchronized small bombs shook Bangalore, India's high-tech hub, killing two people and wounding at least five others.