Police arrested a third suspect and hunted for two others Saturday in the gang rape and slaying of two teenage cousins found hanging from a tree in northern India, a case that has prompted national outrage.

The three suspects detained in the attack in Uttar Pradesh state are cousins in their 20s from an extended family, and they face murder and rape charges, crimes punishable by the death penalty, said police officer N. Malik. Two fugitive suspects from the same village are also being sought, he said.

Facing growing criticism for a series of rapes, officials in Uttar Pradesh — which has a long reputation for lawlessness — also arrested two police officers and fired two others Friday for failing to investigate when the father of one of the teenage girls reported them missing earlier in the week.

India has a history of tolerance for sexual violence. But the gang rape, which was followed by TV footage of the corpses of the 14- and 15-year-old girls swaying as they hung from a mango tree, triggered outrage across the nation. The father who reported the girls missing, Sohan Lal, has demanded a federal probe.

"I don't expect justice from the state government as state police officers shielded the suspects," said Lal, a poor farm labourer who refused to accept a payment for 500,000 rupees ($8,500 US) offered by the state government as financial help. He told reporters Saturday that he would accept no help until the Central Bureau of Investigation, India's FBI, takes over the investigation.

Two teenage cousins were gang-raped, killed and hung from a mango tree in Katra village in India's Uttar Pradesh state. Two of the four men arrested so far are police officers. (Associated Press) Such government payments are common in India when poor families face high-profile calamities, and Lal's unusual refusal — particularly for a man living in desperate poverty — was likely to focus attention on his demands for a federal investigation.

Rahul Gandhi, a leader of the opposition Congress party, visited families of the victims on Saturday.

"The state has a jungle rule," said Rita Bahugana, Gandhi's party colleague.

Dozens of members of the All India Democratic Women's Association marched Saturday through the streets of New Delhi, India's capital, demanding the immediate arrest of the fugitive suspects and justice for the victims. "Enough is enough. Women will not tolerate such atrocities any longer," the protesters chanted, asking state authorities to take crimes against women seriously.

Uttar Pradesh officials initially appeared caught off guard by the reaction to the attack on the two girls. On Friday, the state's top official mocked journalists for asking about it.

"You're not facing any danger, are you?" Uttar Pradesh Chief Minister Akhilesh Yadav said in Lucknow, the state capital. "Then why are you worried? What's it to you?"

Ashish Gupta, a state inspector-general of police, pointed out to journalists that 10 rapes are reported every day in Uttar Pradesh, which has 200 million people and is India's most populous state. Gupta said 60 per cent of such crimes happen when women go into the fields because their homes have no toilets.

The girls in the latest incident were attacked in the tiny village of Katra, about 300 kilometres from Lucknow. They disappeared Tuesday night after going into fields near their home to relieve themselves.

Lal went to police to report them missing, but he said they refused to help. That infuriated his neighbours, who, once the bodies were discovered, refused to allow them to be taken down from the tree until the first arrests were made.

The girls were Dalits, from the community once known as "untouchables" in India's ancient caste system. The fired policemen and the men accused in the attack are Yadavs, a low-caste community that dominates that part of Uttar Pradesh. The chief minister is also a Yadav.

Also in Uttar Pradesh state, police on Thursday arrested three men for brutally attacking the mother of a rape victim after she refused to withdraw her complaint.

Growing public anger

The attack, in the town of Etawah, followed the May 11 rape of the woman's teenage daughter. The arrests were made after the mother filed a complaint with authorities.

Official statistics say about 25,000 rapes are committed every year in India, a nation of 1.2 billion people. Activists, though, say that number is just a tiny percentage of the actual number, since victims are often pressed by family or police to stay quiet about sexual assaults.

Indian officials, who for decades had done little about sexual violence, have faced growing public anger since the December 2012 gang rape and murder of a young woman on a moving New Delhi bus, an attack that sparked national outrage.

The nationwide outcry led the federal government to rush legislation doubling prison terms for rapists to 20 years and criminalizing voyeurism, stalking and the trafficking of women. The law also makes it a crime for officers to refuse to open cases when complaints are made.