Nirbhaya Convicts: Mukesh Singh, Vinay Sharma, Akshay Singh and Pawan Gupta are on death row.

The four Nirbhaya case convicts, who are to be hanged on February 1, have given no reply to questions about meeting their family for the last time or willing their property, sources at Tihar jail said on Thursday.

The rules allow death row convicts to choose which family member they want to meet for the last time and when. Convicts are also asked to state whether they want to leave their property to anyone.

Sources say on both counts, the convicts - Mukesh Singh, Vinay Sharma, Akshay Singh and Pawan Gupta - were silent. This was seen to suggest that they remain hopeful of buying more time.

Eleventh-hour petitions by the convicts resulted in their execution, first scheduled on Wednesday, being deferred to February 1 at 6 am.

Nirbhaya's parents are among those who have denounced the delayed execution of the convicts, sentenced to death for the 2012 gang-rape, torture and murder of a 23-year-old medical student.

Yesterday, the government approached the Supreme Court for a change in guidelines in death row cases so convicts cannot keep delaying the sentence by exploiting legal options. The current rules are skewed towards convicts and allows them to "play with the law and delay execution," the centre said in its petition.

The government wants the Supreme Court to set a deadline for the filing of petitions after the death warrant is signed.

After a judge ordered their execution on Wednesday at 7 am, the Nirbhaya convicts extracted more time after one of them filed a mercy petition.

Even after the mercy petition is rejected by the President, 14 days have to be given to the convict until execution.

Last week, another convict, Pawan Gupta, went to the Supreme Court with the claim that he was below 18 when the crime was committed. The claim was rejected.

Six men were arrested after the young woman was brutally assaulted on a moving bus in south Delhi for hours, tortured with an iron rod and thrown off the vehicle. One man was found hanging in his jail cell and the sixth, the youngest, just short of 18 at the time, was released after three years in a reform home.