London: Girls as young as 13 are being given contraceptive implants at school without their parents' knowledge. Nurses insert devices into their arms which temporarily prevent pregnancy by releasing hormones into the blood.

Last year, 1,700 girls aged 13 and 14 were fitted with implants, while 800 had injections which have the same effect. The 2010/11 NHS figures also show that 3,200 15-year-old girls were fitted with implants, and 1,700 had injections.

But under strict patient confidentiality rules, staff are banned from seeking the permission of parents beforehand or even informing them afterwards.

Not all the girls would have had the procedures at school. Some may have been treated at family planning clinics or a GP surgery.

But MPs and campaigners say the scheme is morally wrong and violates parents' right to protect their children.

Both forms of contraception can bring on unpleasant side-effects including weight gain, depression, acne and irregular periods. The jabs have also been linked to bone-thinning, although experts say fractures are unlikely if they are used only for a short time.

The implants and injections are being offered to girls in nine secondary schools and three sixth form colleges in Southampton under a scheme run by NHS Solent. The sexual health clinics also offer other forms of contraception, advice and tests for infections.

The trust introduced the scheme in 2009 to tackle high rates of teenage pregnancy, which are amongst the worst in the country.

It is not known how many other areas are operating similar policies, but in 2008 the Department of Health wrote to 21 authorities with high rates of teenage pregnancy, including Bristol, Manchester, Newcastle upon Tyne, Rotherham, Nottingham and Peterborough, urging them to increase the uptake of implants and jabs.

The implants last for three years before they need replacement. Injections are effective for up to three months.

Outrage

One mother whose 13-year-old daughter was given an implant at a Southampton school said: "I feel really angry. I agree that teaching teenagers about sexual health and contraception is very important but this is a step too far. I have spoken to a lot of parents at the school and they were horrified to find out this was happening."

Tory MP Nadine Dorries said: "This is a violation of parents' right to protect and nurture their children. It is a surgically invasive procedure being imposed on children without parents' knowledge."