India's main opposition Congress party said Friday that its bank accounts had been frozen by the tax department just weeks before the expected announcement of national elections.

"We were told that the accounts of India's main opposition party have been frozen," Congress party spokesman Ajay Maken told a press conference.

Maken said India's Income Tax Department had issued a payment demand for 2.1 billion rupees ($25.3 million) in relation to a probe of its income tax filing for the 2018-19 financial year.

He insisted the party had done nothing to warrant such a penalty and suggested the action was aimed at sidelining it ahead of elections.

"When the principal opposition party's accounts have been frozen just two weeks before the announcement of the national elections, do you think democracy is alive in our country?" he asked reporters.

Critics and rights groups have accused Prime Minister Narendra Modi's government of using law enforcement agencies to selectively target its political foes.

Congress party leader Rahul Gandhi, scion of the dynasty that dominated Indian politics for decades, was convicted of criminal libel last year after a complaint by a member of Modi's party.

His two-year prison sentence saw him disqualified from parliament for a time until the verdict was suspended by a higher court, but raised concerns over democratic norms in the world's most populous country.