Karti Chidambaram, 47, is at the heart of the allegations against his father.

Highlights P Chidambaram, arrested last night, accused of facilitating foreign funds

Son Karti Chidambaram at the heart of the allegations against him

They were named by former media bosses Peter, Indrani Mukerjea

Arrested former Finance Minister P Chidambaram's son Karti Chidambaram said today that his father's arrest was nothing but an attempt to silence the government's most vocal critic.

"I was summoned 20 times, raided four times. They still don't have a case," Karti Chidambaram told reporters as he arrived at the Delhi airport this morning from Chennai. He said he would participate in a Congress protest in the city.

Karti Chidambaram, 47, who was elected to parliament from his father's long-time constituency Sivaganga in the national election earlier this year, is at the heart of the allegations against his father.

Investigators say it was at his urging that Mr Chidambaram, as Finance Minister who headed the Foreign Investment Promotion Board (FIPB) at the time, facilitated a huge infusion of foreign funds into media company INX Media in 2007 and for this, Karti received kickbacks.

P Chidambaram and his son were named by INX co-founders Peter and Indrani Mukerjea, who are currently in a Mumbai jail in connection with the murder of Indrani Mukerjea's daughter Sheena Bora. Mr Chidambaram has denied the allegations and so has Karti.

"I have never met Peter and Indrani Mukherjea or anyone associated with them," Karti Chidambaram told reporters.

"The only time I met her was during the CBI interrogation. I have never met anyone in FIPB, I don't know the process of FIPB," he added. "I only saw Indrani when they made me confront her at Byculla Jail (in Mumbai)."

Last night, as his father was dramatically arrested in Delhi, Karti was in Chennai. Asked by reporters who was behind it, he said: "Yes, of course, all of this is being done by BJP. Who else? You think Donald Trump? No."

CBI officials say he will be allowed to meet his father.