Seven "crude" bombs have exploded across the Indian city of Bangalore, killing a woman and injuring around 20 others.

Police spokesman MR Pujar said: "There were seven low-intensity explosions. Some of them were in crowded areas. At least one person was killed and 15 to 20 were injured."

Bangalore Commissioner of Police Shankar Bidri said: "In all these cases they have created the blast using timer devices. Explosives have also been used, in quantity equal to one or two grenades."

TV pictures showed one small shopping centre with broken windows and its concrete floors broken in pieces. Rubble littered another site.

India has suffered a wave of bombings in recent years, with targets ranging from mosques and Hindu temples to trains. It is unusual for any group to claim responsibility for attacks.

But Islamist militant groups in Pakistan and Bangladesh are often blamed for bomb attacks in India.

The groups are intent on fanning hatred between Muslims and Hindus in India, and damaging a fragile peace process between New Delhi and Islamabad.

Bangalore hosts the bulk of India's IT and outsourcing business and is home to more than 1,500 top firms, including offices of large global firms such as Microsoft, Intel and IBM.

In May, eight bombs, many strapped to bicycles, ripped through a crowded shopping area in the western city of Jaipur, killing 61 people and injuring hundreds more.

Police said that attack bore some hallmarks of the Bangladeshi militant group Harkat-ul-Jihad al Islami (HuJI).

© Independent Television News Limited 2009. All rights reserved.