In a letter written to Modi by former Delhi Chief Minister Arvind Kejriwal, the party has asked him to make the election expenses of the BJP public and also the people who fund the party's election campaign.
"You are a Prime Ministerial candidate, but why are you still quiet over the issue. A common man wants to know whether if your party forms government and you become the Prime Minister, would you bring down the gas price from 8 dollar per unit to 4 dollar?" said the letter, which Kejriwal read out to the media in a press conference.
He also questioned the silence of the BJP and the Congress over the issue and wondered whether they were quiet because of their close relations with Reliance Industries Ltd Chairman Mukesh Ambani.
"Parimal Nathvani, the group president of the Mukesh Ambani companies, was recently elected to Rajya Sabha with your help.
"This creates suspicion over your relations with Mukesh Amabani. What is your relation with Mukesh Ambani?" the letter added.
Kejriwal alleged that the UPA government is being run by Mukesh Ambani and if Modi comes to power, would his government be also run by the Reliance Industries Chairman? he asked.
"You in your speeches talk about bringing back the money from Swiss banks, but the Ambani brothers have money in these banks. If you have good relations with the Ambanis and if they fund you, then would you bring back the black money," he said.
The former Delhi Chief Minister questioned the election funding of the BJP and the Congress.
"Helicopters and private jets are being used whenever you and Rahul Gandhi travel within the country and abroad. As per the news reports, the aircraft services you and Rahul Gandhi use are free of cost. Spending in your election rallies are worth crores of rupees. Some people say Mukesh Ambani funds you. Is that true?" he said.