Two people were critically wounded on Thursday in a powerful bomb blast near a Food Corp of India (FCI) depot in the heart of Assam's main city Guwahati.
A police spokesperson said the explosion took place near a rice depot of FCI where dozens of labourers were working. FCI's executive director was kidnapped April 17.
"Two of the workers were seriously injured. We suspect it to be an improvised explosive device (IED) planted near the boundary wall of the FCI depot," a police official said.
The two were shifted to a hospital with multiple wounds.
"The casualty would have been higher, but most workers were a little away from the wall and were taking shelter under a tree due to the scorching heat," the official said.
Police blamed the outlawed United Liberation Front of Asom (ULFA) for the blast.
The ULFA, fighting for an independent homeland since 1979, on April 17 kidnapped FCI executive director Phulchand Ram and have sought Rs 2 million as ransom for his release.
"Maybe the blast was a warning by ULFA to pressurise the department to cough up the ransom money," the official said.
The ULFA in the past two months has staged at least half-a-dozen bomb attacks in Guwahati, killing one person and wounding at least 30 more.
The ULFA was also blamed for a string of attacks in January that killed about 80 people, 61 of them Hindi-speaking migrant workers in eastern Assam.
An Indian home ministry report released earlier this week said 99 civilians were killed by ULFA in 156 incidents in Assam from January to March 31.
New Delhi launched a massive military offensive against ULFA after the strikes, killing 55 rebels and arresting 553 more cadres since January.
More than 10,000 people have lost their lives to insurgency in Assam during the past two decades.