Intelligence inputs had been received that terror groups were likely to "create trouble" at either Varanasi's Sankat Mochan or Kashi Vishwanath temples, Home Ministry officials said.
"Following the riots in Lucknow a few days ago, security was tightened in some of the religious places of worship and information was passed on to the state police," an intelligence official said.
Police have confirmed four deaths and said at least 17 people were injured.
The injured have been admitted to the SS Hospital near the Benaras Hindu University.
"It was obviously a well planned attack as the attackers chose on Tuesday (an auspicious day for Hindus). A large number of devotees milled around the temple," a Home Ministry official said.
No damage was reported to the idols or structure of the temple.
Following the twin blasts, the police cordoned off the area and evacuated hundreds of devotees from the temple.
A high-level meeting of Home Ministry officials was immediately convened to evaluate the impact of the blast, even as red alerts were sounded in several parts of the country, including in the national capital and in Maharashtra, Bihar, Orissa and Gujarat.
Home Minister Shivraj Patil was expected to visit Varanasi.
{{/usCountry}}Home Minister Shivraj Patil was expected to visit Varanasi.
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