The UK's first Anti-Slavery Commissioner Kevin Hyland has made Nigeria a high priority, as latest figures reveal a rise in the number potential trafficking victims brought to the UK.
Here are some facts about the issue.
Hundreds of Nigerians brought into the UK every year for forced labour or prostitution, this includes men, women, and children.
Latest figures from the National Crime Agency reveal that more than 2,000 potential trafficking victims were referred to the authorities in 2014 - 244 of whom were from Nigeria.
The Home Office estimates there are between 10,000 and 13,000 potential victims of slavery in the UK.
The Modern Slavery Act, under which Kevin Hyland's post was established, was passed this year. It is the first legislation of its kind in Europe.
Nigeria is one of the world's main source countries of human trafficking. It is also the key African source country for women trafficked for the sex trade.
The country's Edo State is the hub of its trafficking crisis.
Around half those arrested for trafficking in Edo State are women.
Italy is the most popular destination for Nigerian trafficking. It is estimated there are as many as 10,000 Nigerian prostitutes.
Nigeria's National Agency For The Prohibition of Trafficking in Persons (NAPTIP) was set up in 2003.
To date, NAPTIP have rescued 6000 victims - but in 2014 only 19 traffickers were convicted.
Video report by ITV News presenter Julie Etchingham: