Maharashtra police on Monday said that they were looking at both Hindu and Muslim extremist groups in the investigation of Malegaon blasts that killed 31.
Analysts said that the devastating attack would mark a significant watershed if involvement of Hindu hardliners was proved.
"We're keeping our minds open to any kind of involvement," said PK Jain, the district's police chief. "The investigation is quite widespread."
He denied that the intelligence community had ignored threats from Hindu hardliners after a series of attacks were blamed on Islamic terrorists, including July's Mumbai train blasts that killed nearly 190 people.
Investigators blamed those blasts on Islamic rebels opposed to New Delhi's rule in Kashmir.
"Whatever splinter groups there are, they are very much under watch," Jain said. But he admitted that the investigation had not moved far since Friday's attacks.
"We released sketches of two suspects. That's the only headway that we've made," he said. "There are other leads that we are investigating."
Bombs attached to bicycles had gone off outside a mosque at Malegaon as thousands of worshippers were coming after attending Friday prayers to mark Shab-e-Bharat.
The attack is being viewed as a deliberate attempt to hit Muslim worshippers or to spark wider disturbances in Maharashtra.
There has been no claim of responsibility for the Malegaon blasts and the government has not identified any suspected group.