At least 29 people have been killed in a string of bomb attacks in the western Indian city of Ahmedabad, a day after fatal explosions in Bangalore.
The blasts on Saturday in Ahmedabad's crowded old city, dominated by its Muslim community, wounded more than 100 people.
At least 16 small bombs exploded. One was in a metal tiffin box, used to carry food, another apparently left on a bicycle.
On Friday, eight bombs exploded in quick succession in the southern city of Bangalore, killing at least one person and wounding six others.
"This has been done by some terrorist group which wants to destabilise the country," the central government's junior home minister Shriprakash Jaiswal told the Sahara news channel.
There were two separate series of bombings, the first near busy market places, the second succession of bombs went off 20 to 25 minutes later around a hospital.
One television channel showed a bus with its side blown up, shattered windows and the roof half-destroyed.
"The bus had just started when the blast happened," said P. K Pathak, a retired insurance official who was travelling in nearby bus.
"Many people standing on the exit door fell down. There was fire and smoke all over. We got down from our bus and rushed to help them."
Ahmedabad is the main city in Gujarat, the scene of deadly riots in 2002 in which 2,500 people are thought to have died, most of them Muslims killed by rampaging Hindu mobs.
Both states targeted in the bomb attacks are ruled by the Hindu-nationalist Bharatiya Janata Party and are among the country's fastest-growing.
Suspicion is falling on Islamist militants intent on destabilising India by fanning tensions between Hindus and Muslims, and police were deployed in Ahmedabad on Saturday to maintain calm.
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, but India says it suspects militant groups from Pakistan and Bangladesh are behind many of the attacks.
