The Centre on Thursday night issued an alert to all states for maintaining tight vigil, especially along Indo-Pak border, following assassination of former Pakistan Prime Minister Benazir Bhutto.

The Border Security Forces, guarding the Indo-Pak borders, were asked to remain vigilant following the killing of Bhutto, a Home Ministry spokesman said.

"All states have also been advised to maintain vigil," the spokesman said.

Officials in the Home Ministry termed the advisory as a precautionary measure to prevent any untoward incident.