The Congress also demanded setting up of the National Election Fund to which any person may make a contribution.
Addressing a press conference at the party headquarters, Congress Rajya Sabha MP and party spokesperson Abhishek Manu Singhvi said: "According to Centre for Media Studies, the BJP spent over Rs 28,000 crore (or 45 per cent) of the Rs 60,000 crore spent by all political parties during the polls."
The amount the BJP spent during the Lok Sabha polls is about one-third of the country's education budget, 43 per cent of the health budget, 10 per cent of the defence budget and about 45 per cent of the MGNREGA budget, he said.
"Even the amount of Rs 24,000 crore spent by the BJP government over the Namami Gange project is less than the election expenditure of the BJP," Singhvi said.
The Congress leader said this is an issue about fairness during elections and giving equal opportunities to everyone. He said democracy is a part of our core structure which is dependent on free and fair elections.
"This is possible only by providing a level playing field and only if political parties are given equal opportunities," the Congress leader said.
Demanding answers from the BJP over its electoral expenditure, Singhvi said: "They (BJP) must explain the source of their money. They should explain whether it is white or black money as they spent such a huge amount after demonetisation."
Firing salvos at the BJP, Singhvi questioned: "Did the maximum amount of the said amount come from electoral bonds?"
Singhvi's remarks came after a Delhi-based think tank in it's report claimed that the BJP was the biggest spender in the 2019 Lok Sabha polls, accounting for 45-50 per cent of the nearly Rs 60,000 crore spent. The report also said that the Congress spent about 15-20 per cent of Rs 60,000 crore during the elections.
The Congress leader said in the last 20 years, involving six Lok Sabha between 1998 and 2019, the election expenditure had gone up by around six times from Rs 9,000 crores to more than Rs 55,000 crores.
"The sheer scale of this humongous expenditure should scare us and compel us to think of taking corrective steps to build a stronger democracy," he said.
He also claimed that 10 to 12 per cent of voters acknowledged receiving cash "directly" and two-third had acknowledged that voters around them also received cash for their vote.
"The greatest challenge to free and fair elections is the Election Commission's inability to prevent the use of black money in election campaigns and the use of inducements to influence voters," he said.
( With inputs from IANS )