Robert Vadra, 50, is being questioned over alleged money laundering.

Businessman Robert Vadra, accused in money laundering case, is being questioned by the Enforcement Directorate in Delhi today as a part of investigation into alleged illegal property deals.

About two hours before he appeared before the probe agency, he wrote in a Facebook post this morning that he was on his way to questioning "for the 13th time" after he has been interrogated by the probe agency for "almost 80 hours".

In a message, seemingly aimed at the media, he also wrote that "blatantly and carelessly airing my health matters is not correct", and said after "fighting over baseless accusations for almost a decade", he is "determined on the truth and it is a book in the making, for the world to read and know clearly, my side ..."

The husband of Congress leader Priyanka Gandhi Vadra reached the ED office at about 10:40 am.

Ahead of the questioning, he wrote: "As I make my way for the 13th time, post almost 80 hours with the Enforcement Directorate, answering any number of questions, amidst sensation and unnecessary drama around, I stay focused and calm," Robert Vadra, 50, wrote on Facebook.

Mr Vadra faces allegations of money laundering in buying a property in London worth 1.9 million pounds. He has denied the allegations of possessing illegal foreign assets and termed the probe a "political witch-hunt" against him.

Last week, he had skipped his scheduled appearance before the probe agency citing bad health.

On Monday, a Delhi court allowed him to travel to the US and Netherlands for six weeks for treatment of an illness.

In his social media post earlier today, Mr Vadra, apparently sent out a message to media: "But blatantly and carelessly airing my health matters is not correct... But my time spent with people with worst problems, ailing, blind and orphaned kids to see them still smile, gives me the strength to go on ...."

He also hinted he was documenting his fight over "baseless accusations". "Physically situations can change, but ones honest mind cannot. I'm determined on the truth and it is a book in the making, for the world to read and know clearly, my side ...," his post read.

The 50-year-old had earlier claimed he was being "hounded and harassed" to sub-serve political ends.