More than 500 women have fallen pregnant despite using a popular contraceptive implant, according to new figures.

Thousands had the £90 Implanon implant fitted, which was designed to stop women getting pregnant for three years by releasing hormones into the bloodstream from a tiny tube in their arm.

But 1,600 women complained about the device to the medicines watchdog, including 584 who said they had unwanted pregnancies, according to figures obtained by Channel 4 News.

The Medicines and Healthcare products Regulatory Agency (MHRA) confirmed it had received a total of 1,607 adverse drug reaction reports linked to Implanon, relating to 2,888 incidents of suspect reactions in users.

Nine of the 584 women who reported an unwanted pregnancy used the terms "device failure", "device dislocation", "device ineffective" and "device difficult to use" to describe their experience.

Others reported scarring and problems with removing the 40mm long implant, it said.

Channel 4 also said 14 women had made claims against their local health trust and said the NHS had paid out more than £200,000 in compensation to women who fell pregnant or were injured by the implant.

Implanon has since been replaced by manufacturers MSD with Nexplanon, which has a new preloaded applicator and can be detected by X-ray or CT scan.

June Raine, a director at the MHRA, told Channel 4: "We worked closely with the company to enable the new version to be developed. They are fully aware of all the concerns that we have."

A lawyer for some of the women claiming for personal loss and damage said many had not realised the preloaded applicator had not released the implant.

Stephanie Prior, partner of Anthony Gold Solicitors, said: "Nexplanon has a new preloaded applicator which is designed to reduce the risk of insertion difficulties and it is radio-opaque so that it can be identified on an X-ray or CT scan if necessary.

"I have clients who fell pregnant as they were unaware that the Implanon device had not been inserted into their arm and they suffered psychological difficulties as a consequence of falling pregnant and later miscarrying or having to make the difficult decision to terminate the pregnancy."

In a statement, manufacturers MSD said: "MSD is confident in the efficacy and safety of Implanon, a contraceptive medicine that has been prescribed to women since its initial approval in September 1999.

"The basis for successful use of Implanon is a correct and carefully performed subdermal insertion of the implant in accordance with the product instructions.

"If the implant is not inserted in accordance with the instructions and on the correct day, this may result in an unintended pregnancy. In addition, no contraceptive is 100% effective.

"Post-marketing events are reported voluntarily from a population of uncertain size. It is generally not possible to reliably establish the frequency or establish a causal relationship to the use of Implanon.

"Therefore, accumulated reports cannot be used to calculate incidence or to estimate drug risk. For these reasons, it would be inappropriate to discuss numbers of reports.

"MSD encourages consumers to speak with their healthcare providers if they have any questions about contraceptive options and to report any adverse experience associated with any MSD medication."