Sonia and Rahul Gandhi have been accused in the National Herald case.
The BJP on Wednesday took a dig at Congress chief Sonia Gandhi and her son Rahul Gandhi over being asked to appear for questioning in a money laundering case by the Enforcement Directorate.
"Have you ever seen a criminal say I'm criminal? They'll of course deny it. Documents are proof. If a chargesheet is filed, you'd approach court to get it quashed, but they sought bail. It means they're guilty," BJP chief JP Nadda said.
The Enforcement Directorate (ED), which investigates financial crimes, has summoned the Gandhis, the Congress said earlier in the day.
While Sonia Gandhi, 75, has been asked to depose before the federal agency at its headquarters in central Delhi on June 8, Rahul Gandhi has been asked to appear on Thursday.
Congress leader Abhishek Manu Singhvi told at a press conference that Sonia Gandhi will comply with the summons.
Rahul Gandhi, 51, has written to the probe agency to postpone the date to after June 5 as he is not in the country, Mr Singhvi and another Congress leader Randeep Surjewala told reporters.
The ED's move is linked to a nine-year-old complaint that accuses the Gandhis of forming a shell company and illegally gaining control of properties worth $300 million.
"A disgusting and cowardly conspiracy is being hatched against the leadership of the Indian National Congress to mislead the country," the Congress party said in a statement that condemned the notice sent to the Gandhis.
"The entire party and every worker will stand shoulder to shoulder with them, and we will fight and win this attack on the country's democracy," it said.
The assets in question had belonged to a firm that published the National Herald newspaper, founded in 1937 by India's first prime minister, Jawaharlal Nehru, who was Rahul Gandhi's great-grandfather.