In an advisory to 28 states and four federal territories the Home Ministry asked local authorities to step up security especially for leaders of political parties taking part in the April-May parliamentary elections, officials said.

'There are tip-offs we have from the Intelligence Bureau which state terrorists (militants) could try and strike in a big way at public rallies,' a top home ministry official told AFP.

Leaders likely to be targeted are ruling Congress party chief Sonia Gandhi, her son, Rahul, Hindu nationalist leader Lal Krishna Advani and others, the Press Trust of India added, citing the bureau's security advisory.

More than two million security personnel will be deployed during the April-May balloting but security agencies say militants could try to strike when candidates are with their potential voters.

'We have learnt our lessons from the Rajiv Gandhi tragedy,' the official said, referring to the 1991 suicide attack that killed the former premier at a political rally in India's southern Sriperembudur town. -- AFP