Under the reforms, teenagers can receive the injections or implants without their parents' knowledge, and those considered at risk of unplanned pregnancies will be advised by their school-based clinics to use these methods of contraception aimed at rendering them infertile for three years, London's Sunday Times says.

Letters from health and education ministers demand 'urgent action' from heads of councils and primary care trusts to bring about 'an overall increase in the uptake of long-acting reversible contraception (Larc)', the Telegraph reports.

'Larc is an incredibly effective method. It is much underused and we expect training and funding to help improve access to it,' said Ms Julie Bentley, the chief executive of Family Planning Association in Britain, in defending the policy.

The health department is also to provide funding for teenagers to be sent cellphone text messages containing contraceptive advice and to take part in confidential video conferences with sexual health advisers in an attempt to cut abortions, The Times says.

Britain has higher rates of under-age pregnancies than anywhere in Europe, and only around 7 per cent women have contraceptive jabs or implants, which are more widely used in America.

The government wants to see a big rise in the contraception uptake because it has identified failures by teenage girls to take the daily pill correctly as one reason for soaring pregnancies.

Ministers want to double the number using Larcs after being told by regulators that they could save around £100 million (S$224 million) a year if 15 per cent of women used the methods.

The National Institute for Health and Clinical Excellence has estimated the move would cut unplanned pregnancies by 73,000 a year.

In total, 20,289 abortions were carried out last year on girls under 18. One in three secondary schools now has drop-in clinics where children can receive condoms, the pill, the morning after pill and, increasingly, contraceptive injections.

According to official figures for 2007/8, there are 1,200 girls aged under 15 taking long-acting contraception, as well as 2,900 15-year-olds and 11,500 girls aged 16 or 17, the Telegraph said.

But the move is already under criticism from many quarters, and critics feel that injections and implants will not protect against the rampant spread of sexually transmitted disease.

Some health experts say the drugs are unsuitable for girls who are still growing.

'There are concerns that using them over long periods might have an impact on bone growth,' said Dr Hans Christian Raabe, a GP and medical coordinator of the Council for Health and Wholeness, a Christian organisation.

He also questioned the effectiveness of the plan. 'I have not seen a single convincing study to show that the provision of contraception leads to a reduction in teenage pregnancy. What is needed is behavioural change,' he argued.

Some parents have also voiced their opposition to the plans.

Mr Kevin Taylor, whose daughter became pregnant at 14, said despite what his family had gone through he would not have wanted his daughter to have the jab.

'There does seem to be a need for this kind of facility, but I think combined support from parents, teachers and health workers will have more of a positive impact in the end.'