A report published by the Inter-Departmental Ministerial Group on human trafficking found that 946 potential victims of human trafficking were referred to the National Referral Mechanism (NRM) last year. Of these, 712 were adults and 234 were children.

This compares with 710 referrals in 2010, of which 524 were adults and 186 were minors.

The report said there has also been an increase in the number of children being forced into crime, including street begging.

It said the UK has recently had its first organ harvesting cases, with one involving the planned sale of a victim's kidneys.

The Child Exploitation and Online Protection Centre (Ceop) estimates there are approximately 300 child trafficking victims in the UK per annum.

The report said that organised criminal gangs within countries including China, Nigeria, Vietnam, Slovakia and Romania now pose the greatest threat to the UK, where they exploit their victims for sex, labour and domestic slavery.

The Government is working with these countries to tackle the problem at its source by lobbying for changes to their laws.

The report said that over the past two years, work has been done to train border staff, police and healthcare workers to better identify, support and protect those who may be victims of trafficking.

Airlines including Virgin Atlantic and Thomas Cook are training cabin crew to look for signs and a 24-hour confidential line has been set up for crew to report concerns to Border Force before a plane lands in the UK.

Police and prosecutors are also working together to gather tactics on child sexual exploitation cases and ensure young victims are fully supported throughout the criminal justice process.

The NRM was set up in 2009 as a framework for identifying victims of human trafficking and ensuring they receive the appropriate help.