Indian federal Home Minister Shivraj Patil said the government had "bits of information" before Saturday that an attack was being planned but did not know a "time and place."
He declined to blame militants.
India has suffered a series of recent deadly blasts that authorities have blamed on Islamic militants seeking to upset a peace process between India and Pakistan and stir Hindu-Muslim violence.
Various militant groups are accused of recruiting in Pakistan, Bangladesh and among India's 140 million Muslims.
The blasts in Hyderabad were condemned by Britain and the US, which said they would support India in the fight against extremism.
"India has shown great resolve and courage in the face of extremist threats," US State Department spokesman Tom Casey said in statement.
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