A combative Rahul Gandhi today challenged Prime Minister Narendra Modi to institute investigations into what he called "the many allegations flung at me by the BJP and the RSS" and throw him in jail if proved."I want to say this Modiji, it's your government, you have all the agencies. Set them after me. Show your 56-inch chest. Launch an investigation against me and if you find anything in six months put me in jail," the Congress vice-president said at a function to mark the 98th birth anniversary of former Prime Minister Indira Gandhi, his grandmother."But stop using your lackeys to throw dirt at me or my family," Mr Gandhi also said, adding, "The BJP and RSS people have been flinging allegations at my family forever, on my grandmother, my father and my mother. I have been seeing this since I was a child."The 45-year-old leader's attack came days after BJP leader Subramanium Swamy released documents which purportedly showed that Mr Gandhi had listed himself as a British national to set up a company in the UK.The Congress has said the filing was inadvertent. Mr Gandhi did not mention Mr Swamy's allegation or specify what BJP charges he was talking about.The BJP immediately hit back. "Government is probing 2G scam, coal scam, CWG scam... There is no need for Rahul Gandhi to challenge us. Robert Vadra (Rahul Gandhi's brother-in-law) has many investigations on against him," said the BJP's Shahnawaz Hussain, listing what he called "corruption that has happened during the Congress regime."Mr Gandhi's attack today sets the tone for a showdown in the winter session of Parliament that begins on Monday next.The opposition has been galvanised by the massive victory in the Bihar assembly elections this month of the Nitish Kumar-led 'Grand Alliance,' of which the Congress is a part. The BJP was handed a humiliating defeat.Top opposition leaders, including Rahul Gandhi, will be seen together tomorrow in Bihar capital Patna at the oath ceremony of Nitish Kumar and his new council of ministers. In Parliament, the parties are expected to join hands to stall the BJP government's key bills as they have done in the last few sessions.