India's main opposition party, the BJP, says it has postponed a series of meetings after the government warned of a possible attack on its leader.
Mr Advani is a former federal interior minister
LK Advani, who was recently nominated as the party's prime ministerial candidate in the general elections, was to hold meetings across the country.
Elections are not due to be held until 2009, but there has been speculation about snap polls amid differences in the Congress-led coalition.
Mr Advani is a former federal minister.
BJP vice-president Mukhtar Abbas Naqvi told Reuters news agency that the government had told the party about a "credible intelligence input about a security threat to Mr Advani".
He added: "We have deliberated on this issue and decided to postpone the rallies."
Blow to campaign?
The party said it had no information on which group or groups could be planning attacks on Mr Advani.
Karachi-born Mr Advani, 80, is one of the most senior leaders of the Hindu nationalist party.
His critics see him as a symbol of aggressive Hindu nationalism.
But in the eyes of his supporters he remains the "iron man" of Indian politics who brought Hindu nationalism to centre stage and propelled his party to power in Delhi.
Correspondents say the decision to put off the meetings could be a blow to the party's plan to kick-start its election campaign after their win in Gujarat state in December.