A senior ED ' title=' ED '>ED official related to the probe told IANS: "We questioned Chidambaram's PS, K.V.K. Perumal about the dealings of Chidambaram and other financial, property and company details.

He said Perumal can be called for questioning on Thursday also.

Chidambaram is under probe by the Central Bureau of Investigation (CBI) and ED ' title=' ED '>ED over alleged alleging irregularities in the FIPB clearance granted to INX Media for receiving overseas funds of Rs 305 crore in 2007 during his tenure as the Finance Minister at the alleged instance of his son Karti Chidambaram.

Chidambaram and his son were named by INX Media co-founders Peter and Indrani Mukerjea, who are currently in jail in Mumbai in connection with the murder of Indrani's daughter Sheena Bora, in February last year.

According to the ED ' title=' ED '>ED sources, the agency suspects the father-son duo of owning several immoveable properties and over 16 bank accounts in other countries, which they are trying to identify to get find out the money trail.

The ED ' title=' ED '>ED probe has also highlighted how persons connected with shell companies executed a will in favour of Chidambaram's grand-daughter.