NEW DELHI (AFP) - Delhi police questioned a former high-flying UN diplomat and Indian government minister late Monday in connection with his wife's murder, a case that has dominated local media headlines.

Sunanda Pushkar was found dead in a five-star hotel room in the capital last January, two days after she alleged on Twitter that her husband Shashi Tharoor had been having an affair with a Pakistani journalist.

Pushkar, married to Tharoor since 2010, had been taking medication for various illnesses and early autopsy results suggested she may have overdosed on anti-depressants and sleeping pills.

But earlier this month, Delhi Police Commissioner Bhim Sain Bassi said new medical reports had led investigators to register a case of murder "against unknown persons".

Television footage late Monday showed 57-year-old Tharoor leaving his New Delhi residence flanked by security guards, pursued by a huge media scrum.

Later images showed him sitting across from a few officers, gesticulating with one hand, at a police station near the luxury Leela Palace hotel where his wife's body was discovered.

Some reports indicated that the interrogation could resume on Tuesday.

Days after his wife's death was registered as a murder, Tharoor described himself as "a bereaved husband" who would not engage in "public polemics", adding that he would fully cooperate with investigations.

Pushkar's death had initially triggered intense speculation that she had committed suicide after being humiliated by her husband.

But a year on, dozens of 24-hour news stations have devoted relentless coverage and analyst debates over Tharoor's possible role in the murder, prompting the former minister to term it a media trial where he was "being defamed now day in and day out".

Her death dealt a severe blow to the image of Tharoor, who was a cabinet minister at the time and remains a member of parliament for the Congress party which lost elections last May.

Also an acclaimed author, Tharoor served as under-secretary general during Kofi Annan's leadership of the United Nations and was a candidate to replace him as secretary-general in 2008.

After being beaten to the post by Ban Ki-moon, he then entered Indian politics as a member of parliament for the southern state of Kerala.

Tharoor had to resign from his first ministerial post in 2010 after revelations that his then-girlfriend Pushkar had been given a free stake in a new Indian Premier League cricket team.