Sunanda Pushkar, wife of Congress leader Shashi Tharoor, died of poisoning, a long-awaited medical report submitted to the police today has confirmed, said sources.

The report, prepared by top doctors at Delhi's state-run AIIMS hospital, draws from the findings of the FBI, which, last year, was sent viscera samples or samples of Pushkar's organs like the large intestine.

"I can say with certainty that the death was not natural," said Delhi Police chief BS Bassi, adding that the report is being studied by a special team of the Delhi Police set up to investigate Pushkar's death.

He also said that the FBI has ruled out the possibility of radioactive poisoning, as suggested in a post-mortem examination.

Pushkar, 53, was married to former union minister Shashi Tharoor when she was found dead in a luxury hotel in Delhi in January 2014, days after she publicly accused him of having an affair with a Pakistani journalist.