A new form of plastic surgery promises to deliver “firm, young-looking breasts that keep their shape over time” by implanting bra-shaped ‘silicone slings’ underneath the skin.

The procedure – which has been approved in the EU but is currently under review in the US – takes forty-five minutes, with surgeons inserting silicon cups underneath the breast tissue and anchoring them to the bones of the rib cage with titanium screws.

Orbix Medical, the company that developed the technology, says that it offers an alternative to breast reduction surgeries with “minimal scarring” but can also replace the ‘unsustainable’ results offered by traditional breast-lifts.

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The first clinical trials were carried out in Belgium in 2009 and over 50 procedures have since been performed throughout Europe, with the ‘internal bra’ gaining its CE mark certifying it for sale in Europe.

The Sun reports that in the UK the procedure might become free to NHS patients who are scheduled for breast reductions or who are suffering from breast cancer. When performed at London’s Guy’s and St Thomas’ Hospital the operation cost £6,000 – approximately £1,000 more expensive than traditional breast implants.

However, surgeons are warning that the operation has not yet been common practice for long enough to determine any possible “side effects”.

“There is a need for clinical trials with adequate numbers and follow ups to prove the efficacy and safety in the long term,” Professor Kefah Mokbel of the London Breast Institude told the MailOnline.

“These cups go under the skin, so the question is do we know the long-term effect to women, will they develop scaring and will the internal bra affect the shape of the breast in the long term? 'It is premature to say it is a solution to the issue of sagging breasts.”

Professor Mokbel added that although the procedure had received CE certification in the EU, this only referred to the safety of the materials being used rather than the operation itself.