The bomb, allegedly planted by militants, went off at 11 PM last night at Ananda Singh Academy, about 2 km from Raj Bhavan, where the President was staying, they said.
No casualty was, however, reported in the blast. Patil is on a two-day visit to Manipur. Police and central forces are conducting round the clock patrolling and forces were deployed at all vulnerable points.
President will today lay the foundation stone of an Information Technology Park at Mantripukhri near here, officials said. Patil would also meet representatives of some social organisations before leaving for Delhi at 11 AM, the sources said.
Meanwhile, normal life was paralysed in the city following the 40-hour strike called by Manipur People's Liberation Front (MPLF) to boycott the President's visit.
The MPLF, formed by three major insurgent organisations of the United National Liberation Front, Revolutionary People's Front and Peoples Revolutionary Party of Kangleipak has been fighting for an ''independent Manipur''.