India's main opposition Congress party on Monday rejected a request from its leader, Sonia Gandhi, that she be allowed to step down, after a rare challenge to the Nehru-Gandhi dynasty, which has dominated the party for seven decades.

Earlier on Monday, the Italian-born widow of former prime minister Rajiv Gandhi had offered to resign as interim leader after almost two dozen senior figures called for better decision-making in the party, which has ruled India for much of its post-colonial history.

Her request was rejected by the party's top decision-making body, the Congress Working Committee, which wants Gandhi and her son, Rahul, to remain in control.

"The CWC, reflecting the overwhelming view and desire of the rank and file of the Congress, unanimously resolved to strengthen the hands of Sonia Gandhi and Rahul Gandhi in every possible way," K.C. Venugopal, a Congress lawmaker, told a news conference.

Prime Minster Narendra Modi's Hindu nationalist Bharatiya Janata Party has dealt the Congress heavy defeats at the last two general elections, leading to disquiet in some sections of the party.

The Congress now controls just a handful of India's 28 states, and the BJP has a comfortable majority in the national parliament.

The party meeting came after 23 senior Congress figures wrote a letter calling for better leadership of the party, two sources said - taken by many as a thinly veiled criticism of the Gandhi family.

The sources said the signatories to the letter wanted the Gandhi family to either play a pro-active role or step down, adding that more than 300 regional Congress politicians also supported the letter.

In the capital, New Delhi, Gandhi family supporters held placards and shouted slogans outside party headquarters.

Sonia Gandhi took over de facto leadership of the party last year from Rahul. His father, grandmother and great-grandfather were prime ministers of India.