The NHS dealt with over 7,000 cases of female genital mutilation (FGM) in 2016, according to a report released Tuesday (7 March).

Of those, over 5,000 were new cases but they have proved difficult for police forces to prosecute.

Since 1985, when FGM became illegal in the UK, there has only been one attempt at a prosecution and not a single person has been convicted.

Inspector Allen Davis, head of Project Azure – London Metropolitan Police's taskforce for sexual offences, exploitation and child abuse – spoke to The Independent about the difficulty in securing convictions.

"We don't know where it's taking place," he said.

"FGM investigations, wherever you are in the world, are complex and challenging so it's not unique to London or the UK."

He added: "The challenge in securing the successful conviction we all strive for, is that it's a home-based crime that is significantly under reported.

"People conducting the FGM are often family members which is an inevitable barrier because the victim is not necessarily going to want to stand up and give evidence."

Among the cases recorded in the UK, 96% of women were aged 17 or younger when FGM was carried out, but almost all (98%) were 18 or over when their FGM case was recorded.

Davis added that the recorded number of cases were just the "tip of the iceberg".

Adding to the difficulty in trying to secure convictions, a majority of families take their daughters abroad to be cut or mutilated (96%).

In 2003, the government expanded the law to make it a criminal offence for UK nationals or permanent residents to take their child abroad for FGM.

Davis and his team now regularly station themselves at airports, where they pull aside families travelling to high-risk countries for FGM for educational conversations.

"We have a lot of tools in our arsenal," he said. "But we are determined to secure a conviction because of the important message it sends out to the affected communities."