Hundreds of British women continue to be wrongly imprisoned, according to a study that condemns the government for not complying with international standards set by the United Nations on treatment of female inmates.

Two years ago, ministers signed up to the Bangkok Rules – new UN standards for the treatment of women offenders. Yet the first analysis into how the UK has performed found that, contrary to its responsibilities, it is wrongly imprisoning large numbers of women who pose no threat to society and is not taking into account the human rights of children affected by their mothers' imprisonment.

The report also confirmed that "shocking" levels of self-harm persist among female inmates. Although monitoring of the UK's 15 women's prisons revealed almost 9,000 self-harm cases in 2011, a significant drop from more than 12,000 the previous year, the figure still remains too high, according to campaigners.

The figures mean that women prisoners account for a fifth of self-harm cases across the UK penal estate despite making up only 5% of the prison population, although the number of female prisoners has fallen during the past year from 4,282 to 3,918.

The report says that the approach to dealing with mental health among female inmates is inadequate and that those in control need to start discussing currently ignored themes including "patriarchy, identity, shame, love, attachment, feminism, loss, abuse and equality of opportunity".

Rachel Halford, director of campaign group Women in Prison, which compiled the report, said: "There are still too many women unnecessarily imprisoned, too many women hurting themselves in prison and too many women reoffending on release."

Prisons reformer Baroness Stern said the findings revealed that six years after the critical Corston report called for a "distinct, radically different, visibly led, strategic, proportionate, holistic, woman-centred, integrated approach", in truth "little has fundamentally changed."

The chief inspector of prisons, Nick Hardwick, warned last year that the way women are treated in prisons will leave England and Wales "aghast and ashamed" in years to come. Hardwick described terrible levels of self-mutilation and admitted that the distressing sights he encountered in one women's unit had kept him awake at night.

Among the inmates interviewed for the report were those who admitted they had contemplated suicide. Others said they felt isolated and that they had no one to turn to. One woman said that the attitude of prison officers "stinks" while another said that there was a "lot of bullying, but staff don't always do anything".

A government review of women's prisons is to be completed by the summer, following the announcement that seven public-sector prisons are to close by March and two more partially shut in England and Wales to help cut costs.

Justice minister Helen Grant said: "The government is committed to addressing women's offending and providing services for their specific needs, making sure they are rehabilitated whether they serve sentences in prison or the community.

"We are putting in place measures that ensure crimes are met with proportionate punishment that is both tough and meaningful in order to reduce reoffending and promote rehabilitation."