Attack appears to have been ordered by village council as punishment for 'unauthorised' relationship and failure to pay fine

Thirteen men detained for the public gang-rape of a 20-year-old woman in a village in eastern India have appeared before a local court, as news of the crime prompted outrage across the country.

The attack in Birbhum district, about 120 miles from Kolkata, appears to have been a punishment ordered by an unelected traditional village council for an "unauthorised" relationship with a married man from another community and the woman's subsequent failure to pay a 27,000 rupee (£260) fine.

A complaint filed by the victim's family described how the council chief told villagers that because the woman could not pay the fine they were free to "enjoy the girl and have fun".

The woman described the protracted attack, which took place on Monday night in front of dozens of onlookers, to local reporters. She said she lost count of the number of assailants, who she said included several of her neighbours.

Officials said medical investigations had backed the woman's claim of repeated rape by between five and 15 men.

"Prima facie the woman was gang-raped by a group of villagers following a kangaroo court where she and her fiance were fined for their so-called extramarital relationship. A complaint was lodged with Labhpur police station against 13 persons. All the accused have been arrested," said the local police superintendent, Birbhum Sudhakar.

Witnesses in the village described how the woman was first raped on a bamboo platform in the centre of the small cluster of mud-walled huts surrounded by fields before being locked in a hut during the night where she was assaulted again.

"She lost a lot of blood and remains in a critical condition. She only survived because she is very tough," said a senior medical official at the hospital where the victim is being treated.

The wife of the married mason with whom the victim had a relationship sold jewellery to pay his fine. The victim's family had no savings.

India has been hit by a wave of sexual violence – particularly gang-rapes – in recent years. Last week a 51-year-old tourist in Delhi was raped by at least five men who attacked while she was walking back to her hotel. There have been several other similar attacks on foreigners.

The gang-rape and murder of a 23-year-old Indian woman in Delhi in December 2012 prompted grief and outrage across the country, with thousands taking to the streets in protests demanding tougher laws, better policing and a shift in cultural attitudes.

The United Nations asked India, the world's second most populous country, to ensure security for women. But although prison terms for rape have been stiffened, stalking made a criminal offence and gender sensitivity programmes introduced for some police officers, little appears to have changed on the ground.

Birbhum is in West Bengal state, which appears to be a particular blackspot. Last month a worker at a gym was abducted and raped by five men in a truck.

In October a woman was raped twice by the same group of men, once as she returned from a police station where she had recorded a statement about the first attack, and was then set on fire. She died of her injuries.

West Bengal is governed by the Trinamool Congress party (TMC), which has been under fire for failing to halt the rising sexual violence. Its chief minister, Mamata Banerjee, is a firebrand political outsider and one of the most powerful women in India.

Derek O'Brien, a TMC parliamentarian, promised "swift action … zero tolerance", in a message on Twitter on Thursday. Opposition politicians in West Bengal called the incident barbaric.

The attack has focused attention on the informal village councils and courts run by local male elders, which are common across much of rural India.

Although technically illegal, they are frequently responsible for inflicting cruel, sometimes lethal, punishments for supposed social transgressions such as marrying without prior consent. Such courts also frequently oblige relatives to take violent action to restore the "honour" of a community.

In one incident four years ago in Birbhum , village elders ordered tribal women to strip and walk naked in front of large crowds as a punishment for "unauthorised" relationships.

Manish Tewari, India's information minister, said in Delhi: "In a democratic country, based upon the rule of law, no vigilantism can be permitted."

In the latest case, those arrested and the victim are from an adivasi or tribal community, who are among the poorest and most marginalised in India. West Bengal has social indicators that are worse than many parts of sub-Saharan Africa.

The council appears to have acted after finding the woman sitting with her lover under a tree. Following the attack, villagers threatened the badly injured victim and her family. Nearly 48 hours later, relatives managed to take her to a clinic from where she was transferred to a hospital. Only then were law enforcement agencies alerted.

The causes of the wave of sexual violence, and its extent, are hotly debated. Many commentators say it is a consequence of the efforts of a growing number of women, even in remote rural areas, to claim basic freedoms denied for centuries. Others point to India's acute gender imbalance, tenacious caste system, apathetic police, inefficient judiciary and entrenched patriarchal culture. Conservatives have blamed "western influences", women's clothing and even fast food.

Activists say that in India as few as one in 100 attacks are reported and counted in official records. Fear of social ostracism and of brutal, unsympathetic police limit the number of victims prepared to complain.

The 13 suspects in Birbhum were remanded in custody. Many villagers blamed the victim. "We will never allow her or her family back here," said Panmuni Tudu, a housewife.