Robert Vadra at the ED office where he is being questioned for the past 3 days. (Image: PTI)

Trouble seems to be mounting for Robert Vadra, brother-in-law of Congress president Rahul Gandhi, as the Income Tax Department probe, according to sources, has established links between him and Sanjay Bhandari.

Bhandari, who was questioned by the Income Tax Department on April 30, 2016, was asked by the interrogators about Vadra's France trip in 2012.

India Today TV has accessed the tax document, which is now part of the Enforcement Directorate's (ED) investigation. Based on the document, investigators had asked Bhandari if the 2012 flight tickets from France to Delhi were booked by him on behalf of Vadra through a booking agency named International Travel Home, based in Delhi's Paharganj.

Bhandari was also asked who made the payment for the flight tickets dated between 13.08.2012 to 19.08.2012.

Bhandari's alleged reply spells trouble for Robert Vadra who is being grilled by the ED for the third day straight.

Bhandari told the I-T Department officers, "Yes, I confirm it was booked on his (Robert Vadra) instruction but as far as I remember, it was purchased but I don't remember how and who made the payments."

Vadra, according to sources, has denied any business association with Sanjay Bhandari. Sources say, Vadra was confronted with this documentary evidence over his alleged association with Sanjay Bhandari.

According to ED, Bhandari received kickbacks in a 2009 petroleum deal and a 2010 defence deal that were used to buy several properties in London worth 12 million pounds.

Sources have told India Today TV that the agency is trying to establish connection better Vadra and Bhandari.

Sources within the agency have also told India Today TV that Vadra was confronted with documentary evidence on day 3 of his questioning but Vadra denied most of the allegations against him. Investigators say that most of responses of Vadra appear to be 'tutored'.

ED sources have also told India Today TV that Robert Vadra allegedly emailed Bhandari's nephew Sumit Chadha giving him clear instructions about the property dealings. Sumit Chadha had sent multiple mails marked to Sanjay Bhandari and Robert Vadra over renovation in the Bryanston property, London. Vadra replied to both Sumit and Sanjay giving clear instructions regarding the properties for which funds were given by Vadra.

The agency also confronted Vadra with the email trail which allegedly shows that the laundered money was allegedly being used to buy properties. ED says they have a trail that allegedly shows that money was used to buy properties for Vadra.