The number of teenage pregnancies across the former Avon area rocketed by 12 per cent in one year.

Records released by the Government revealed 717 under-18s conceived in 2007 – up from 641 in 2006 – and around half of them had an abortion.

Although increases in the number of girls falling pregnant varied across the Bristol region, all areas saw a rise well above the national average of three per cent.

North Somerset reported a rise of 37 per cent followed by Bath and North East Somerset with 14 per cent. Bristol and South Gloucestershire both recorded a seven per cent increase.

However, the Government insists the most accurate way to analyse the figures is to look at the number of teenage pregnancies per 1,000 because it prevents them being skewed by population increases and decreases.

However, that still means there were five more pregnant girls per thousand in Bristol in 2007 than there were in 2006, nine more in North Somerset and three more in South Gloucestershire and B&NES.

Anne Colquhoun, teenage pregnancy strategy coordinator for Bristol, said: "It is disappointing to see a blip in the figures for Bristol when so much work is going on in the city but it's important to remember that these figures are from 2007 and, since then, so much work has been done.

"A year ago, we launched the city's first sexual health service for young people called 4YP. It was created in consultation with young people and has gone from strength to strength – we have 21 drop-in clinics in Bristol schools, 60 venues where young people can get free condoms and 11 4YP-branded sexual health clinics across the city.

"Young people using the service reacted very positively to it, and said that the approachability and accessibility of staff was key to its success."

She added the scheme had been so successful it would now be rolled out across the UK.

The drop-in scheme is being run by Brook Advisory Services in partnership with Bristol City Council and NHS Bristol in 21 educational venues.

Ms Colquhoun added: "We are currently working with young people to better understand the issues in their lives, what they see as the reasons behind teenage pregnancy and then how they want to be communicated with.

"Being able to talk with parents is an ongoing issue and so we really support the leaflet for parents which, was launched last Sunday, and will be in pharmacies in Bristol from March."

The Government has pledged to halve pregnancy rates among under-18s by next year.

Ministers have announced £20.5 million will be made available to promote the use of contraception and encourage young people not to rush into becoming sexually active.

Health chiefs across the country will share £10 million of the fund to ensure contraception is available "in the right places at the right time".

Health Minister Dawn Primarolo, MP for Bristol South said young people needed access to contraception as soon as they become sexually active.

She said: "We are supporting the NHS to offer women of all ages the full range of contraceptive choices, including long-acting reversible methods such as implants and injections, which are virtually 100 per cent effective."

"We're giving local health services more money to come up with innovative ways of making sure young women use their contraceptives properly, such as text message reminders."

But Liberal Democrat children's spokeswoman Annette Brooke said: "It is shocking that in almost half of our poorest areas, our already high teenage pregnancy rate is actually rising.

"The Government has had more than a decade to tackle this problem, but these figures show how spectacularly they have failed.

"Ministers have got to get their act together and introduce high-quality relationship and sex education into the curriculum.

"The longer ministers hide from the issue, the more they fail Britain's young people."