A 20-year-old woman who died after being hit by a car and dragged for “10 to 12 kilometres” amid predawn New Year celebrations in Delhi had been sexually assaulted, her family has alleged while claiming one of the accused is a “BJP leader”.

Delhi’s ruling Aam Aadmi Party and the Congress tweeted pictures of a hoarding from Sultanpuri, where the car hit took place, that purportedly shows accused Manoj Mittal, 27, alongside other local BJP leaders. It gives his designation as “sah sanyojak” (deputy organiser) for Ward 42.

The AAP alleged that the police, who report to the Union home ministry, and the administration were protecting the accused — New Year revellers — because of Mittal’s BJP links.

Mittal and four other young men who were allegedly in the grey Maruti Baleno have been arrested and charged with rash driving and causing death by negligence, where the maximum punishment is two years’ jail.

The police have not explained the omission of the charge of culpable homicide not amounting to murder, punishable by up to a life term.

An eyewitness accused the police of inaction from the outset. He said he had called the police control room “more than 20 times” from 3.15am on Sunday after seeing a car dragging a body and repeatedly making U-turns, but the expected patrol car never came.

“We demand a fair probe as one of the accused is said to be a local BJP leader. We suspect (the victim) was also sexually assaulted by the five accused,” a relative of the woman, who declined to be identified, said while protesting with others outside Sultanpuri police station on Monday.

The woman’s mother alleged her daughter, an employee of an event management company who was returning home from work when she met with tragedy, had been sexually assaulted before the “accident” was staged.

“An accident like that could not have torn off her clothes completely, but she was entirely naked when she was found an hour after the incident. I want a fair probe,” she told reporters.

The National Commission for Women said the panel had taken cognisance of the mother’s allegation and written to the Delhi police commissioner seeking a post-mortem to ascertain if the victim was sexually assaulted.

Officers dismissed the allegation of sexual assault but the police did not comment officially on it, or on the claim that the body was naked when it was found in the Kanjhawala locality around 4.45am.

They said Kanjhawala was 4-5km from Sultanpuri but the car’s repeated U-turns suggested the body was dragged for 10- 12km.

Police arrested the five suspects one by one on Sunday after noting the car’s number from CCTV footage. Apart from Mittal, those arrested are the driver Deepak Khanna, 26, Krishan, 27, Amit Khanna, 25, and Mithun, 26.

Mittal is a ration dealer in Sultanpuri, Amit a bank employee and Mithun a hairdresser, while Krishan works at the Spanish Culture Centre in Connaught Place, the police said. The police said they had taken blood samples to ascertain whether the accused were drunk.

A Delhi court on Monday remanded all five to three days’ police custody. AAP spokesperson Saurabh Bharadwaj told a news conference that Delhi lieutenant governor V.K. Saxena and the police had deliberately concealed the information that Mittal was a BJP leader.

“There is a cover-up in the entire incident because the LG is aware of the involvement of a BJP leader,” he said, demanding Saxena’s dismissal. Bharadwaj accused the police of presenting a weak case.

“The police have registered a case of death due to negligence under Section 304A, which is a bailable section. What about the sexual assault charges?” he said.

The Delhi BJP’s media cell head, Harish Khurana, underlined that the accused had been arrested.

“The guilty should be given the strictest punishment regardless of the party they belong to,” he told PTI.

Deepak Dahiya, a confectionary owner, told reporters he saw the gruesome incident while opening his shop early, around 3.15am, on New Year’s Day.

“Suddenly I heard the sound of a car. I saw something stuck under the car and later realised it was a dead body,” he said. He said he dialled the police emergency number, 112, immediately and alerted the cops.

“I couldn’t tell them whether it was a man, woman or child. I told them there was a body stuck under a car but the vehicle was moving constantly.”

Dahiya said the car made three U-turns and kept returning to the same spot with the body trapped in the undercarriage. He said he had called the PCR van “more than 20 times” but the cops never arrived.

Officers said that CCTV footage showed the car making a U-turn at Kanjhawala, with the body visible under the vehicle.

Claiming to speak on the basis of statements of the accused during interrogation, they said the men had eventually removed the body from under the wheels at Kanjhawala and fled.

Chief minister Arvind Kejriwal has demanded the death penalty for the accused. He spoke to Saxena and urged him to ensure that the most stringent criminal charges were brought against the five. Union home minister Amit Shah has sought a report from the police brass and “asked them to act swiftly in the case without fear”, a ministry official said on Monday night.

On Sunday, Saxena had tweeted: “My head hangs in shame over the inhuman crime in Kanjhawla-Sultanpuri today morning and I am shocked at the monstrous insensitivity of the perpetrators. Have been monitoring with @ CPDelhi and the accused have been apprehended. All aspects are being thoroughly looked into.”

He added: “Even as every possible support/ help and beyond, to the family of the victim will be ensured, I appeal to all to not resort to opportunistic scavenging. Let’s together work towards a more responsible and sensitive society.”