An organisation set up by the actor Ashton Kutcher has identified 2,000 child victims of trafficking in the past six months.

The Hollywood star gave an emotional speech to the Senate Foreign Relations Committee on Wednesday, as he called for more to be done to tackle child sexual abuse.

The 39-year-old co-founded Thorn: Digital Defenders of Children, which builds software to fight human trafficking, with his ex-wife Demi Moore in 2009.

In total, the tool had identified 6,000 victims of modern slavery in six months, he revealed.

The visibly emotional actor, who has two young children with actress Mila Kunis, said: “As part of my anti-trafficking work, I've met victims in Russia, I've met victims in India, I've met victims that have been trafficked from Mexico, victims from New York and New Jersey and all across our country.

"I've been on FBI raids where I've seen things that no person should ever see.

"I've seen video content of a child that's the same age as mine being raped by an American man that was a sex tourist in Cambodia.

"And this child was so conditioned by her environment that she thought she was engaging in play."

Kutcher said his team received a call from the Department of Homeland Security asking for help to find a seven-year-old girl after footage of her being sexually abused was "spread around the dark web".

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"She'd been abused for three years and they'd watched her for three years and they could not find the perpetrator, asking us for help," he said.

"We were the last line of defence. An actor and his foundation were the potential last line of defence.

"That's my day job and I'm sticking to it."

In a more light-hearted moment at the hearing, Kutcher blew a kiss towards Republican senator and former US presidential candidate John McCain.

It came after McCain told the actor: "Ashton, you were better looking in the movies."