Bharatiya Janata Party (BJP) leader Subramanian Swamy said here on Friday said that there are many indications that prove the Delhi Police is under pressure adding that a CBI investigation is inevitable in the case.

"This is something that has vindicated my position and I have been saying this from day one. There are many indications that now prove that Delhi police did not provide the documents to the autopsy committee which proves that they are under some pressure," Swamy told ANI.

"The autopsy also establishes that there was a deep thump mark on her body, like somebody tried to open her mouth. Most of all, there are disturbances in Shashi Tharoor's statement. He also was caught sending emails to the director. We don't have any other option but to order a CBI investigation on this case," he said.

"The Delhi police are a one dimensional police force. This case has international ramifications. The kind of poison which has been found cannot be investigated by Delhi police. This is a Russian poison which is very difficult to detect and the Delhi police is not trained for this," he added.

A report has been submitted by a group of All India Institute of Medical Sciences (AIIMS) doctors on the mysterious death of former Union Minister Shashi Tharoor's wife Sunanda Pushkar, according to which the latter died of poisoning.

This is the second autopsy report in the Sunanada Pushkar case. Earlier, AIIMS Head of the Forensic Department, Dr. Sudhir Gupta had claimed he was pressurised to tamper with the post-mortem report of Pushkar, who died under mysterious circumstances in a posh New Delhi hotel on January 17 this year.

Pushkar, who married Congress leader Shashi Tharoor in 2010, had checked into The Leela Hotel in Chanakyapuri a day before her death.

Tharoor's aides said the couple had checked into the luxury hotel because of renovation work at his Delhi bungalow.

Prior to her death, Sunanda was embroiled in a spat with Pakistan-based journalist, Mehr Tarar, whom she accused of stalking her husband.