NEW DELHI (AFP) - The leaders of India's defeated Congress party, Mrs Sonia Gandhi and her son Rahul Gandhi, admitted personal responsibility on Friday for the disastrous election results which came after 10 years in power.

"We understand that victory and loss is part of democracy," party president Sonia told reporters in New Delhi as preliminary figures showed the Congress heading for its worst ever performance.

"We respect this decision. I take responsibility for this defeat," she added, in remarks echoed by her 43-year-old son, who led national campaigning for the first time.

The leftist Congress has dominated Indian politics since independence, mostly with a member of the Nehru-Gandhi dynasty at its head. The famous bloodline has provided three prime ministers.

But Friday's figures have already triggered speculation about their future after a lacklustre campaign by Mr Gandhi, a former management consultant whose political skills are widely doubted.

"I would like to start by congratulating the new government. They have been given a mandate by the people of this country. We have done pretty badly. As vice-president of the party I hold myself responsible," Mr Gandhi said.

Preliminary results at the end of the marathon six-week election showed the Hindu nationalist Bharatiya Janata Party (BJP) led by hardliner Narendra Modi on track for the first parliamentary majority by a single party in 30 years.