Modern forms of hormonal contraceptives increase the risk of breast cancer by around one quarter, research by Oxford University has found.

The study of almost 30,000 women below the age of 50 tracked cases of the disease among those taking a range of contraception.

The included new generation drugs which people hoped would carry fewer health risks, with evidence suggesting they are less likely to cause strokes and blood clots.

But researchers found that progestogen-only drugs and coils carry at least equal risks as the combined pill, when it comes to breast cancer, in women below the age of 50.

Overall, the increased cancer risk for women taking progestogen-only drugs was 26pc, compared with 23pc for those on combined pills.

This rose to 32pc among those with progestogen-releasing intra-uterine devices, while those with hormonal implants experienced an increased risk of 25pc. Scientists stressed that the overall risks of breast cancer among young women remain low.