The widow of the former Indian Prime Minister, Rajiv Gandhi, has begun her first ever political campaign on behalf of her late husband's Congress Party with a strong attack on politicians who exploit religion as an election issue. Mrs Gandhi was speaking at a rally in the town of Sriperumbud outside the southern city of Madras - just a half kilometre from the place where Rajiv Gandhi was killed by a suicide bomber in 1991. Our India correspondent, Daniel Lak, sends this report:

For the Congress Party, Sonia Gandhi's political debut was a qualified success.

The crowd may not have been as large as organisers predicted, but it was enthusiastic and happy to see Mrs Gandhi on the dais.

She was accompanied by her daughter, Priyanka, whose political ambitions are much speculated about but not known.

Mrs Gandhi said she was publicly campaigning for the Congress, partly because her husband's ideals of unity and fairness were under threat and not because she wanted to run for office herself.

Her words will be taken here as an attack on the Hindu Nationalist BJP - something that will please Congress activists. She also called Congress India's only truly national political force and said it would be unstoppable with the right leadership.

Mrs Gandhi will now spend several more days campaigning across south India in areas where Congress knows it is weak and thinks it can pick up support.

Later she will also turn her attention to the all-important north of the country where Congress has almost disappeared from the electoral map in recent years.

Many observers, even Congress insiders, think her intervention may have saved the party from humiliation in this election, but probably won't be enough to win it.