Five others were injured in the explosion, which occurred just outside the state capital of Imphal, said deputy inspector general of police Clay Khonghai.

"I can confirm that four people have been killed and five are injured. We suspect the involvement of separatists," Khonghai said by telephone from the site of the blast.

So far none of Manipur's several separatist outfits has claimed responsibility for the attack.

Copyright AFP (Agence France-Presse), 2011