Unidentified militants exploded bomb at Congress office in interior Thoubal district of Manipur but no casualty was reported, official sources said on Friday.
Sources said the militants lobbed three powerful bombs at the office late on Thursday night.
While one bomb exploded, damaging office wall and the two others failed to explode, sources said.
In a separate incident, unknown militants hurled two powerful bombs at another Congress office at Nambol in Bishenpur district but both bombs failed to explode, sources said.
The motive behind the crime was not known, sources said, adding that no individual or group has so far claimed responsibility for the incidents, sources said.