According to reports, suspected militants exploded the grenade at Chapaguri area in Lower Asssam district under Bodoland Territorial Area Districts (BTAD) around 8.40 am on Wednesday.
"Two bikers hurled the grenade targeting security personnel and managed to flee from the area," a top police official said.
There has been no report of any casualty.
Security forces recovered a Bajaj Pulser bike near the blast site.
Top police and army officials rushed to the area and launched a search operation against the militants.
Meanwhile, six militant groups, including United Liberation Front of Asom (ULFA-Independence), NDFB(S) and Kamatapur Liberation Organization (KLO) have called to boycott the 67th I-Day.
The Assam Police have sounded a high alert across the state ahead the I-Day celebrations on a probable attack by militants.
"Tight security has been arranged at all parade grounds, markets, public places in the state. As many as 25 additional security companies have been deployed at sensitive areas," Assam Police ADGP (Law and Order) A P Raut said.
In a separate incident, security forces apprehended two hardcore militants of NDFB(S) in Udalguri district on Tuesday night.
Acting on a tip-off, the Udalguri Police had launched an operation at Nepalpara area in the BTAD district and nabbed the militants.
The nabbed militants were identified as Rugen Daimary and Bilian Narzary.
The police recovered one 9 mm pistol, six rounds live ammunition and one Chinese hand grenade from their possession.
(Reporting by Hemanta Kumar Nath)
--IBNS (Posted on 14-08-2013)