New Delhi: The four convicts in the Nirbhaya gangrape case will be executed in Jail No. 3, a senior Tihar Jail official said on Tuesday, hours after a Delhi court issued death warrants against them and declared that they will be hanged at 7 am on January 22.

Sources said the jail authorities will formally approach the Uttar Pradesh prison authority asking for a hangman from the state's Meerut district to carry out the executions.

The hangman, Pawan Jallad, said though no one has spoken to him about the executions, he is ready to do the job to send out a strong message in the society.

According to the Tihar official, the four convicts -- Mukesh (32), Pawan Gupta (25), Vinay Sharma (26) and Akshay Kumar Singh (31) -- will be kept in isolated cells and will not be allowed to interact with other prisoners. Their family members, however, can visit them any time.

The safety of the convicts will be taken care of by the prison authorities and doctors will conduct regular check-ups to keep a check on their physical and mental health, he added.

The four will be executed in Jail No. 3 and the ropes which will be used for hanging them will be brought from Bihar, the official said, adding that the prison authorities are waiting to receive the court order.

Asked if the four would be hanged together, the official said "it is possible".

If this happens, it will be for the first time in the history of independent India that four convicts will be hanged in the gallows site in Jail No. 3.

In last three decades, since 1991, 16 convicts have been hanged to death in India including Dhananjoy Chatterjee - for rape and murder of 14-year-old school girl, Yakub Memon and Afzal Guru.

In last 20 years, four people were hanged to death out of which only Dhanajoy Chatterjee was charged of rape and murder of a school girl while the other three were terrorists.

Three of the convicts are lodged in Jail No. 2, while one is in Jail No. 4, he added.

Nirbhaya, a 23-year-old paramedic student, was gangraped and brutalised on the intervening night of December 16-17, 2012, inside a moving bus in south Delhi by the four men, including two others, before being dumped on the road.

She died on December 29, 2012, at Mount Elizabeth Hospital in Singapore.

Of the six persons convicted, one allegedly committed suicide in jail and another, a juvenile, was released from a reformation home after serving a three-year term.

Mukesh, Pawan, Vinay and Akshay can still move a curative petition before the Supreme Court.

With no hangman in Tihar, the sources said, the jail authorities will write to the prison authority of neighbouring Uttar Pradesh asking for a hangman.

"We had earlier written to the prison authority of Uttar Pradesh seeking services of a hangman from Meerut. Now that the death warrant has been issued, we will be writing to the prison authority again," they said.

When contacted, Jail Superintendent of Meerut prison V P Pandey said he has not yet received any letter from Tihar authorities.

"Last month, we had received a letter asking us to keep Pawan Jallad ready but there is no fresh communication. The Delhi court warrants were issued only this evening, maybe we will get the letter for sending him by tomorrow (Tuesday)," he said.

Speaking to reporters in Meerut, Jallad said he is ready to execute the four convicts and is awaiting orders.

"I do not have any information regarding the execution, nobody has spoken to me yet. If anyone approaches me, I am ready to do the job. Earlier, I was asked to be ready for the executions on December 16.

"Those who were involved in this brutal incident must be hanged which will send out a strong message in the society," he said.

Deputy Commissioner of Police (Special Cell) Pramod Singh Kushwaha, who headed the special investigation team (SIT) which probed the Nirbhaya gangrape case, said the execution of the four convicts will be a "real tribute" to her.

"This judgement will send a strong message to criminals and nobody will dare to commit such a crime in future," he said.

All members of the SIT did their best which resulted in consistent judgement by the court, he said.

The gangrape of 23-year-old, who came to be known as 'Nirbhaya', the fearless one, sparked outrage across the country. Repulsed, people took to the streets across the country, demanding justice for her and better safety measures for women.

The case led to toughening of India's rape laws.

(With inputs from agencies)