WIKIPEDIA/GETTY/SVT Women have been warned not to go out alone at night in Sweden

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Officers in picturesque Östersund issued the astonishing warning after gangs of "foreign" men went on the rampage, attempting to rape women in the street and even groping a group of 10-year-old girls at a bus stop. The shocking announcement will heighten concerns around the effects of mass migration on Sweden, which has been struggling to integrate more then 150,000 predominantly Muslim migrants. Women in the tiny lakeside town of Östersund, in central Sweden, have been terrorised by sex attacks with six such incidents being recorded in the last two weeks.

In all of the cases the male attackers, often acting in gangs, were described as being "of foreign appearance". The attacks come as Swedish authorities have begun sending increasing numbers of migrants to a refugee reception centre in the small town because all accommodation further south has already been filled. Speaking at an extraordinary press conference yesterday police chiefs issued a stunning warning to women, telling them Östersund is now so unsafe they should not go out after dark alone.

GETTY Sweden has taken in more than 150,000 migrants in a year

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Regional police chief Stephen Jerand said the attacks were unusual because none of the perpetrators appeared to be drunk, adding that officers have witnessed a "worrying trend" in the town. He said: "The cases of the sexual harassment and attempted rapes have involved groups of up to three people. What stands out is also that none of these perpetrators have been under the influence. "Now the police are going out and warning women against travelling alone in the city. We have seen a worrying trend. "This is serious, we care about the protection of women and that is why we are going out and talking about this." The most recent assault took place in the early hours of Sunday morning, when three young men attempted to rape a woman in the town centre.

GETTY However, there is growing concern over the societal toll of mass migration

SVT Some reacted with fury to local police chief Stephen Jerand's warning

According to police they wrestled her to the ground shortly after 1am and tried to rip her trousers off, before she managed to fight back and escape. The perpetrators have been described as "tall, slim, aged 18-25 and speaking Swedish with a foreign accent". Just a few hours later, police received another report of a lone woman being attacked by a young man in the same neighbourhood. A police report states that an unknown man in his late 20s "whose appearance was described as foreign" suddenly lunged at the woman and attacked her. Detectives said that the man walked up to her and punched her in the face before throwing her to the ground, pushing her head into the tarmac, and running off.

SVT Ostersund is a quiet town with a population of just 45,000

We have seen a worrying trend Regional police chief Stephen Jerand

Most shockingly of all police are probing a disturbing incident in which a group of men tried to grope four ten-year-old girls who were waiting at a bus station in central Ostersund. Police also highlighted an additional four cases in the past two weeks, including a lone woman assaulted by three men, and a report of a group of ten-year-old girls being harassed by men in central Östersund. The warning was today defended by police, who said they had learnt from previous criticism when they failed to alert the public to the threat of migrant sex attacks.

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Mr Jerand admitted officers had failed to protect a number of women who were sexually assaulted at a music festival in Stockholm, with the subsequent cover-up of the crimes shocking the nation. He said: "Police have previously been criticised for not going out and informing people, I think of the example of the criticism over the We Are Stockholm festival. "Therefore we choose now to go out and tell people. We would, of course, not scare people, but at the same time, we have a responsibility to tell people what is happening." But the warning was widely criticised by women's rights advocates, who expressed concerns that Sweden's hard fought gender equality is being undermined by a blind obedience to the dogma of multiculturalism. Local government commissioner Ann-Sofie Andersson said it was fundamentally wrong to ask women to "adapt" to the needs of sex abuse monsters.