On one side of the marketplace, it was carnage. As the Hindu mob descended, Muslim-owned stalls selling car parts were slowly reduced to debris and ashes. But just 100 metres away stood two police stations.

As the mob attacks came once, then twice and then a third time in this north-east Delhi neighbourhood, desperate stallholders repeatedly ran to Gokalpuri and Dayalpur police stations crying out for help. But each time they found the gates locked from the inside. For three days, no help came.

“How could they set fire to our market in such a horrific way, while it is so close to two police stations, and not be stopped?” said a shopkeeper, who asked to remain anonymous for fear of reprisals. “But if I make any complaint against the police and if they know my identity, I will face very serious trouble.”

Graffiti that appeared on a wall in a mostly Muslim area in north-east Delhi last week: ‘Revolution loading … Who do you call when the police murders?’ Photograph: Shaikh Azizur Rahman

Since the riots broke out in Delhi at the end of February, the worst religious conflict to engulf the capital in decades, questions have persisted about the role that the Delhi police played in enabling the violence, which was predominately Hindu mobs attacking Muslims. Of the 51 people who died, at least three-quarters were Muslim, and many Muslims are still missing.

“During the recent riots in Delhi the role of the police has been very reprehensible,” said SR Darapuri, a retired senior police officer from Uttar Pradesh. “They not only openly sided with the Hindu mobs attacking Muslims but also used brutal force against them. They purposely failed to respond to the SOS calls from the Muslims trapped in many violence-hit areas. Evidently, the role of the police has been communal, unethical and unprofessional.”

Delhi’s police are under the direct control of the ruling Bharatiya Janata party government, specifically the home minister and party president, Amit Shah, who is one of the most fervent advocates of the BJP’s Hindu nationalist agenda, which aims to establish India as a Hindu, rather than secular, nation. As a result, the political agenda of the BJP government of the prime minister, Narendra Modi, which is widely seen as vehemently anti-Muslim, appears to have become firmly entrenched in the mindset of the Delhi police, which is already an overwhelmingly Hindu force.

In the weeks that have followed the riots, the alleged bias of the police has extended to accusations of a cover-up to protect the Hindu rioters and a widespread refusal to file or investigate complaints made by Muslim victims.

A Muslim-owned tyre market in Delhi, which was burned down by Hindu mobs during February’s violence. The market is about 100 metres from two police stations. A police station sign, in Hindi, is visible on the top left. Photograph: Shaikh Azizur Rahman

Delhi police did not respond to repeated requests for comment but speaking in parliament last week, Shah praised the “commendable” job done by the Delhi police and said that “people should not look for religion in riots”. The police themselves claim they did everything in their power to restore law and order. But those who took part in the riots on the Hindu side tell a very different story.

The catalyst for the riots is widely acknowledged to have been a comment by Kapil Mishra, a BJP leader, who on 23 February issued a public ultimatum declaring that if the police did not clear the streets of a protest against a new citizenship law seen as anti-Muslim, his supporters would be “forced to hit the streets”.

Ravinder, a 17-year-old who works in his father’s property business and is part of India’s lower-caste Gujjar community, said he and other young Hindu men had heard Mishra’s call to action against the Muslim community, and began to mobilise on the morning of 24 February without any fear of police reprisal.

“There was a clear instruction of catch-and-kill action against any Muslim we could spot,” said Ravinder. “I was in a group of around 15 boys. Many senior brothers said to us that police would not take any action against any member of our community and we could attack the people on the other side [Muslims] the way we liked.”

Ravinder described how he and a group of seven men had captured a Muslim rickshaw driver in his 40s, beaten him with wooden sticks and metal rods until he appeared dead, and then threw him in an open drain while police stood by. He also said the police had instructed them to destroy the CCTV cameras as they marauded through the streets.

A car park in Delhi’s Shiv Vihar district, which was set alight by mobs during February’s riots. Photograph: Shaikh Azizur Rahman

“Some policemen were standing just a few metres away,” said Ravinder. “They did not say anything to us. They turned their faces away from us. We understood that police would not intervene if we turned violent against any Muslim … and a large section of the police all along backed us throughout.”

His account was echoed by a Hindu priest from Bihar state. The Brahmin, who spoke on condition of anonymity, said he had witnessed young Hindu men in his neighbourhood, who were all BJP supporters, declare that the “police brothers are with us” as they gathered stones, iron rods, knives, machetes, wooden sticks and guns ready to attack Muslims.

“The men were displaying weapons openly,” the priest recounted. “One young man with a pistol shouted: ‘Brothers, we are on a mission in the interest of the nation. Our [BJP] leaders have given the call to come out in the open ... There is nothing to worry about. Join us and increase our strength.’

“They were mobilising other youths to come out with all types of arms. This was in the presence of police. It was clear that police were on our side,” he added.

While the authorities have denied that police were in any way involved in the violence, video footage captured during the riots and corresponding witness testimony shows police accompanying and encouraging the Hindu mobs or even taking part in pelting Muslims with stones and destroying CCTV cameras.

One piece of mobile phone footage, which went viral laid bare the anti-Muslim bigotry of Delhi police. On 24 February, in one of the first clashes of the riots, police officers were captured beating five Muslim men who had not taken part in any violence. They kicked and hit them with sticks until their bodies were limp and broken, and then as the wounded men lay in the street, police forced them to sing the national anthem to prove their “loyalty” to India.

Rafiq lying in bed at home in Delhi’s Kardampuri area. The Muslim tailor was beaten in police violence against protesters in February. Photograph: Shaikh Azizur Rahman

Among the men was 23-year-old Mohammad Faizan, who had gone out looking for his mother that day. Though an innocent bystander, after their beatings and public humiliation at the hands of the police, Faizan and the others were then taken into police detention, where they received no medical attention. By the time he was released over 24 hours later, Faizan’s condition had deteriorated. He died in hospital the next day from internal injuries, though his family has still not been given the report of the postmortem examination.

Sitting on the floor of the one-room house she shared with Faizan, his mother, Kishmatoon, 61, could not contain her grief, stroking the bed where he had once slept. “He was completely innocent,” she wept. “They cannot show any evidence which shows my son did anything unlawful that day. Yet the policemen caught and beat him mercilessly and finally he died from the beatings.

“They are policemen and I am poor and powerless,” she said. “I cannot seek justice for my son’s murder by police in any court in this country.”

Yet as the violence escalated across north-east Delhi and hundreds of thousands of phone calls began to flood into the police helpline, in most cases no police came. While Delhi police have claimed they did not have the manpower to respond to the scale of calls, accounts given to the Guardian suggest many made by Muslims purposefully went ignored.

Sanjida, 32, who owned a bakery in Shiv Vihar that was destroyed by mobs, described how she had called the police as the attackers descended and was told by the officer who picked up the phone: “You voted for Kejriwal, call Kejriwal for help,” referring to Arvind Kejriwal, the progressive chief minister of Delhi whose party recently beat the BJP by a landslide in the Delhi state elections with huge backing from the Muslim community.

Others described how when they had called the police helpline, they had been told: “You wanted Azadi [freedom], this is it.’’

A ruined mosque in Shiv Vihar, north-east Delhi, which was attacked by Hindu rioters on 25 February. The rioters came in lorries with gas cylinders that were used as explosives. The rioters attacked all four mosques of Shiv Vihar in the same way. Photograph: Shaikh Azizur Rahman

Most victims of the riots now believe that police complicity in the violence means they will never receive justice. Mehmood Pracha, a lawyer who is providing free legal assistance to riot victims, alleged that the police were now trying to prevent the mobs that carried out the violence being brought to account.

“Police are using pressure tactics and trying to ensure that no complaint is filed against the rioters,” said Pracha. “We have received hundreds of complaints from Muslim people that police are threatening people, including women and children, that if they filed complaints, they would be implicated in false cases.”

Even a retired Muslim policeman said no officers had responded to dozens of calls as his house was looted in the riots. Mahmood Khan, 66, who worked for Delhi police all his life, had his house raided three times by Hindu mobs. He said no police had responded to his calls, his letter to a senior officer had gone unanswered and the police had initially refused to let him file a report about the damage.

“Maybe they will pretend to look for the culprits but in the end they will be protected,” said Khan. “We are Muslims. There is no justice for us.”