NEW DELHI: The CBI on Monday sent an extradition request for Nirav Modi 's brother Neeshal Modi in Rs 13,578 crore Punjab National Bank scam.Official sources said the extradition request has been sent to ministry of home affairs, which will forward it to ministry of external affairs and then it will be formally handed over to Belgian authorities.Neeshal, a Belgian national, is said to be living in Antwerp, where a large amount of funds is said to have been laundered by the brothers. An Interpol Red Corner Notice had already been issued earlier against Neeshal, restricting his travel to different countries.Sources said authorities are trying to bring back both Nirav and Neeshal Modi along with Mehul Choksi and top absconding executives of their companies for facing trial in India. Officials added that India has an extradition treaty with Belgium so getting him shouldn't be a problem. "Once the extradition documents reach Belgium, the authorities there would be liable to trace and arrest him," said a CBI officer.It is alleged that Neeshal Modi was "actively" involved in the scam. He is also alleged to be the beneficiary of funds siphoned off, instrumental in introducing dummy partners and changing pattern of partnership structure of companies.He is also said to have formed shell companies to support his brother's illegal activities. Neeshal Modi (34), along with Nirav Modi and uncle Mehul Choksi, fled the country in the first week of January this year, weeks before the scam surfaced in Brady House branch of PNB in Mumbai.While Nirav Modi has been in the UK, Choksi is in Antigua and Barbuda where he has taken a citizenship. Replying to several e-summons sent by CBI and ED, both Nirav and Neeshal Modi have refused to come back to India and cooperate with investigators.CBI has already filed a chargesheet against the accused persons alleging that they fraudulently had letters of undertaking of more than $2 billion issued through PNB's Brady House branch between during 2011 and 2017.