"I ask the Prime Minister: How much percentage of culprit are you ?", Gadkari said at a BJP rally referring to Singh''s comment at his interaction with Editors of TV channels last week.
Gadkari also accused the Congress of shying away from taking action on black money stashed in foreign banks for fear that it would "blacken the faces" of its leaders.
The BJP chief said that when the Supreme Court had asked the Government why it was not disclosing names of people having such accounts, it was told any such move "is not in the interest of the nation."
He pointed out there is a United Nations resolution, allowing countries to get back such money stashed abroad, but that the UPA government had not ratified it.
"The Congress is not implementing it, because if they do that, their leaders'' faces will get blackened; they would not be in a position to show their face", he alleged.
"After NDA comes to power in 2014, we will bring back this entire money", he said, adding these funds would be used for the welfare of poor, farmers and for road development and to link rivers Ganga and Cauvery to bring prosperity to the region.
Referring to Prime Minister''s remarks on compulsion of coalition governments, he accused Manmohan Singh of "outsourcing" a Department (Telecom) to an alliance partner.
"Is it coalition dharma to encourage corruption and ''adharma", he asked.
On the 2G scam, he quipped: "(D) Raja (former Telecom Minister) bajayega UPA ka Baaja".(Raja will spell doom for UPA).
Gadkari also said the country''s borders are not safe.
China is building airports and developing roads in Pakistan Occupied Kashmir, he said and referred to "Maoist rule" in Nepal. Naxalites are trying to create a ''red zone'' from Pashupatinath in Nepal to Tirupati in Andhra Pradesh, he said.
He charged Congress with indulging in ''appeasing'' terrorism, noting that Afzal Guru, the main man behind the Parliament attack, was yet to be hanged even six years after his conviction by the Supreme Court.
"Appeasement to terrorism is being given the name of secularism", Gadkari said.