Deputy Prime Minister Lal Krishna Advani, touring the sites of Monday's bomb blasts, said Pakistan had been waging a "war of terrorism" against India for years.

But he stopped short of blaming Islamabad directly for Monday's blasts, which killed 50 people and wounded 148, saying he did not know who was responsible.

"Our neighbor's war of terrorism... is against the whole of India," Advani told reporters.

Islamabad condemned Monday's bombings, which coincided with a thaw in relations between nuclear-armed India and Pakistan.

Advani said Pakistan should prove its sincerity by handing over suspects wanted by New Delhi for past bombings.

"Only then can we believe that they meant what they said yesterday when they condemned the attacks," he said.

Pakistan Information Minister Sheikh Rashid Ahmed told Reuters India was indulging in "non-serious talk."

"We are not involved in the war in India," Ahmed said. "We don't need it and it is India's own problem."

Police have blamed the outlawed Students Islamic Movement of India working together with the banned Pakistan-based Kashmiri separatist group Lashkar-e-Taiba for the bombings.

India stepped up security nationwide Tuesday to head off any religious violence but police said there were no reports of clashes between Hindus and minority Muslims.

Among the victims were eight men from western Gujarat state, where at least 1,000 people, mostly Muslims, died last year in revenge killings following an attack on a train carrying Hindu pilgrims from the northern holy town of Ayodhya.