The film Sold, starring Gillian Anderson, is to be screened at the launch of a new anti-trafficking campaign in Nepal.

Executive produced by Emma Thompson, Sold tells the story of a 13-year-old Nepali girl sold to a brothel in India, with Anderson as the US photographer who tries to rescue her.

Children's rights organisation Childreach Nepal will host a screening of the film to launch its Taught Not Trafficked campaign at a conference in Kathmandu.

As many as 20,000 children are estimated to be trafficked out of Nepal every year. Most are girls aged between 12 and 18, with many being sold to work in the sex industry in India.

Firoz Patel, chief executive officer of Childreach International, said: "Trafficking is a global problem that affects us in the UK as well as in the rest of the world.

"It is estimated that over 20 million people, over five million of whom are children under 18, are in some form of slavery.

"Nowhere is this more felt than in Nepal, where tens of thousands of children, especially girls, get sold into forced work from which there is little hope of escape.

"In supporting children to stay in education, we can make a difference, strengthening local communities and economies that will better withstand the lure and the threat of the trafficker."

Childreach Nepal's conference Educating Girls: Investing In The Future is supported by Unicef Nepal.

The event will be attended by members of the Nepal government, as well as child rights and educational organisations.

Gillian Anderson said: "Working on this sensitively told film and with young women who have themselves experienced the unbelievable trauma of abduction and trafficking has opened my eyes to the horrors these young people face on a daily basis as well as the often life threatening danger those working at the charities put themselves in to free these innocent victims from modern day slavery.

"We also need to work on tackling the causes of trafficking and preventing it from happening in the first place. Education is key, which is why I'm proud to support the Taught Not Trafficked campaign with Childreach International."