The BSP has declared that it did not receive any funds from voluntary contributions -- above or below Rs 20,000, sale of coupons or electoral bonds, or unknown sources of income, the ADR said.

Though the amount of donations from electoral bonds has been highlighted for the national parties, state parties also get a substantial amount of money from electoral bonds, the NGO noted.

Between the financial years 2004-05 and 2022-23, the national parties collected Rs 19,083 crore from unknown sources, it said.

On its latest analysis for the financial year 2022-23, the ADR said among these unknown sources, the major contributor was income from electoral bonds, constituting a "massive 82.42 per cent of the total income from unknown sources".

Further scrutiny revealed that out of the total income from unknown sources, Rs 1,510 crore came from electoral bonds, it said.

In addition, the Congress and the CPI(M) have also declared a combined income of Rs 136.79 crore from the sale of coupons, constituting 7.46 per cent of the income from unknown sources, its analysis showed.

The BSP received Rs 29.27 crore from other known sources of income which included bank interest (Rs 15.05 crore), membership fees (Rs 13.73 crore), gain on sale of immovable property (Rs 28.49 lakh) and interest on income tax refund for 2021-22 (Rs 20.65 lakh), the organisation said.

The total income of the six national political parties in the financial year 2022-23 is Rs 3,076.88 crore, it said.

Donations from voluntary contributions below Rs 20,000 formed 10 per cent of the income from unknown sources, totalling Rs 183.28 crore.

Currently, political parties are not required to reveal the names of individuals or organisations giving less than Rs 20,000.

The ADR has suggested stringent measures to enhance transparency and accountability in political funding.

It advocates for full disclosure of all donors under the Right to Information (RTI) Act and proposes that the mode of payment for all donations, regardless of the amount, be declared in the audit reports submitted to the Income Tax Department and the EC.

Moreover, the EC's recommendation to grant tax exemption only to parties contesting and winning seats in elections, along with the disclosure of donors contributing above Rs 2,000, has received support from the ADR.

In a landmark verdict delivered last month, ahead of the Lok Sabha polls, the Supreme Court scrapped the government's electoral bonds scheme of anonymous political funding, terming it "unconstitutional" and ordering disclosure of the names of the purchasers, value of the bonds and their recipients.