57-year-old Tharoor was rushed to the hospital at around 3am after he complained of severe chest pain, anxiety and palpitation, sources at the AIIMS said.

The Union minister was admitted to the ICU of the cardiothoracic centre of the AIIMS and a number of investigations including ECG have been carried out on him.

Doctors said he was brought to the hospital with a "cardiac condition" but he is stable now.

A team of doctors are monitoring him at the ICU, the sources said.

Sunanda, who was upset over an alleged extra-marital affair between her minister husband Tharoor and a Pakistani journalist, was found dead in a five-star hotel room last night.

The body of 52-year-old Pushkar, a woman entrepreneur who married Tharoor in August 2010, was found in mysterious circumstances in luxury Leela Palace hotel in South Delhi.

Police sources speaking on condition of anonymity said they suspect it could be a case of suicide.

Delhi Police spokesman Rajan Bhagat had said inquest proceedings have been initiated by the sub-divisional magistrate of the area. Any death within seven years of marriage is legally required to be investigated by the sub-divisional magistrate.

Pushkar and Tharoor were at the centre of a raging controversy in the last two days when reports emerged that she was upset over reported text and tweet messages between her husband and Mehr Tarar, Pakistani journalist.