A bomb exploded near the Raj Bhavan in Aizawl on Monday night on the eve of a protest demonstration planned by some political parties against a proposal of the Delimitation Committee on assembly constituencies.

Superintendent of Police Zorammawia said security was beefed up following the explosion, which took place around 2200 IST.

The police suspect the explosive to be gelatin and investigations are on.

Some political parties, including the Janata Dal (United), have alleged that the proposal to delimit the 40 assembly constituencies in the state, to ensure that minorities like the Chakmas and Brus have more legislators, was the handiwork of Governor Amolak Rattan Kohli.