New Delhi: The Corporate Affairs Ministry has found prima facie proof of irregularities by Bharatiya Janata Party President Nitin Gadkari's Purti group, according to sources. Sources say the returns filed by the Purti group and other investor companies indicate irregularities in their business transactions. The Mumbai Registrar of Companies is probing the 15 companies which have links with Gadkari. Sources also say that the money trail leads to Kolkata and the companies have been given two weeks to explain.