The five are bus driver Ram Singh, his brother Mukesh, fruit seller Pawan Gupta, gym instructor Vinay Sharma and bus cleaner Akshay Thakur. All of them are now in Delhi's Tihar Central Jail.

They have been charged with murder, gang-rape, unnatural offence, destruction of evidence, attempt to murder, kidnapping, causing hurt while committing robbery, dacoity with murder, and common intent.

The chargesheet, filed in the Saket court of Metropolitan Magistrate Surya Malik Grover, who posted the matter for Jan 5 for taking cognizance. The case is expected to be taken up by a fast track court.

Thursday's development comes 18 days after the six gang-raped and tortured the 23-year-old physiotherapy intern in a moving bus, leading to multiple-organ failure and her death.

They also assaulted her 28-year-old male friend. Both were thrown out of the bus after around 40 minutes, naked, bleeding and shivering. The friend will be the main witness in the case.

Public prosecutor Rajiv Mohan sought a day's time to file an e-chargesheet, saying documents to be annexed were bulky.

The operative 33-page chargesheet is part of a much bulkier document, which includes the victim's statement, details of the accused, evidences and forensic reports.

An application was filed for concealing the identity of the victim.

"All the original documents have the name of the victim, so we are moving the application for concealing her identity," the application said.

Police urged the court to have in-camera proceedings but the court said it would decide the issue later.

The main formal charges would highlight that Ram Singh, a short-tempered man involved in crime, was instrumental in the Dec 16 assault.

He also used an iron rod on the victim with the help of Thakur and the minor co-accused, a police officer said.

The driver and Thakur will be accused of destroying evidence as they washed the bus after the incident at Noida, near Delhi, the officer said. They also burnt the victims' clothes.

According to police, it was the minor who first passed lewd comments on the woman after they boarded the bus around 9.15 p.m.

The attackers were drunk and were on a joy ride.

They brutally beat the woman and her friend with an iron rod when they resisted them. Then they gang-raped the woman. The young woman fought the accused and bit Thakur, Ram Singh and Sharma.

The chargesheet, police sources said, would cite 30-40 witnesses including doctors who treated the gang-rape victim in Delhi and Singapore.

Ramadhar Singh, a man who was robbed by the six on the bus minutes before the gang-rape, would also testify as a witness.

All the accused were arrested between Dec 17-21 following a nationwide outcry over the crime, which also triggered protests in several cities. In Delhi, protesters clashed with security forces.

The gang-rape led the government to promise speedier trial of rape cases and amendments in rape laws.

Prime Minister Manmohan Singh and Congress president Sonia Gandhi were at the airport when the gang-rape victim's body arrived from Singapore. She was cremated in Delhi.