NEW DELHI (AFP) - India's top court on Thursday (Dec 12) ordered an inquiry into the police shootings of four rape-murder suspects, as speculation grew that four other men convicted of the infamous 2012 Delhi bus gang-rape would be executed soon.

The men were killed in what police claimed was a "shootout" last week, raising fresh concerns about the alleged use of extrajudicial killings by Indian authorities.

The accused had been re-enacting their alleged rape and murder of a 27-year-old veterinarian in the southern city of Hyderabad in late November.

A former Supreme Court judge was appointed to head the inquiry, alongside a retired High Court judge and a former head of the Central Bureau of Investigation (CBI), India's equivalent to the FBI.

The probe was tasked by the court to complete its investigation in six months.

The rape and murder of the young woman sparked widespread demonstrations and calls for swift and tough justice, with people taking to the streets and cheering after the men were shot dead.

The huge public outcry recalled the rape and murder of a woman on a Delhi bus in 2012, where nationwide protests also broke out against the high levels of sexual violence and India's broken criminal justice system.

There has been increased speculation in local media that the men convicted of the Delhi bus assault would be hanged as soon as Monday, the anniversary of the attack.

Neighbouring Uttar Pradesh state has been asked to provide the jail with two hangmen on short notice, the Press Trust of India reported.