Here are the 10 developments of the story:
"From where did Vijay Mallya procure such funds? Was sinking ship (Congress) helping sinking airline (Kingfisher)," questioned BJP spokesperson Sambit Patra.
Mr Patra said it was clear that the "hands" that pulled the strings to ensure that Mr Mallya received loans belonged to Dr Singh and Mr Chidambaram.
The BJP also implied the role of "10 Janpath (Congress president Sonia Gandhi)" in pulling strings and said: "Sonia and Rahul Gandhi should come out in public to say at whose behest the loans were sanctioned to Kingfisher Airline."
In a letter in October 2011, Mr Mallya appears to thank Dr Singh for meeting him a month before and asks him to help him getting financial backing from banks like the State Bank of India.
A month later, the businessman wrote another letter to the Prime Minister's office, asking for urgent help to stop the branding of Kingfisher as a "Non-Performing Asset".
The former Prime Minister and Mr Chidambaram, who gave their assessment of the country's economy today ahead of the Budget, said they were only forwarding requests as a matter of routine.
"You are talking about one letter that was leaked....there are hundreds of letters that come to the government every day," said Mr Chidambaram.
The Congress has accused the BJP-led government of helping the businessman duck the law. "The real question to be asked is who permitted Mr Mallya to escape? Who pardoned the loan? Didn't the BJP vote for him and bring him to the Rajya Sabha?" said the party's spokesperson Randeep Singh Surjewala.
Mr Mallya flew to Britain in March last year in the middle of efforts by banks to recover nearly 9,000 crores in unpaid loans to Kingfisher Airlines, which stopped flying in 2012.
Indian agencies have since made several attempts to bring back the businessman, who faces court warrants. Mr Mallya has said he is living in "forced exile".
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