The Directive was adopted by last December by the European Parliament but the UK had refrained from opting in until this week, arguing that the UK's existing laws already cover many of the provisions contained in the Directive.

This claim was refuted by several charities, including CARE, which said there were “significant areas of non-compliance”, including a lack of representation for trafficked children in the UK.

The Directive states that a guardian should be appointed to children whose parents are not in the position to represent them.

It also broadens the definition of trafficking to include forced begging, an issue in the UK with the trafficking of the Roma people.

While the UK has hitherto had the power to prosecute in cases where trafficking occurred into, within, or out of the UK, the Directive gives it the power to prosecute in cases where British citizens were trafficked outside of the UK.

Welcoming the decision to opt-in, CARE chief executive Nola Leach said: “The Directive contains vital steps forward in making the UK a more hostile place for criminal gangs to operate, whilst ensuring that people who have been trafficked receive adequate care and protection.

“I am delighted that the Government has finally lived up to its promise to prioritise tackling this horrendous exploitation.”

The Archbishop of York, Dr John Sentamu, has also been pressing the Government to opt-in. He said the Government had made the “right decision”.

“I am delighted that the Government has finally reached the right decision and will now opt in to the EU Directive on Human Trafficking," he said.

"For some time I have been raising the matter with the Home Secretary, calling on her to opt in to the EU Directive to ensure we have a united front across Europe tackling the evil of human trafficking.”