It was part of International Justice Mission's (IJM) annual Freedom Sunday which encourages churches to unite in prayer for the issue.
CEO of the Christian charity, David Westlake, told Premier it's a very critical problem as 40 million men, women and children are trapped in brutal slavery today.
"If I can put that a little bit into context, in the next hour, 120 children will be sold, and they'll be sold into sweatshops and brothels and factories.
"And of course we know that children belong in families and playgrounds and schools.
"This is a critical issue. It's 120 children in the next hour, and an hour after that, and the hour after that, and every hour of every day, people made in God's image that he wants to restore to wholeness and to give them a future and a hope."
More than 100 churches took part in Freedom Sunday.
Sheila from a church in Yorkshire said: "My prayer is that I do justice to this important subject, the work of IJM and that the Lord's voice will be heard. At almost 80, this is a huge privilege for me to do this and to raise awareness of this powerful, effective ministry."
According to IJM, in Ghana, traffickers sit in the congregations of churches in fishing villages around Lake Volta- the lake in which children as young as three are forced into hard, dangerous labour and face a daily risk of drowning.
IJM said hundreds of courageous pastors will be challenging the traffickers to stop, and they'll be encouraging their congregations to take stand against this abuse.
Westlake told Premier why slavery is an issue for Christian to address: "Our fundamental story is a God who sets captives free. We know that for ourselves, he sets us free from sin and from shame, and from the things that have wounded us and hurt us and held us back. But our whole story through the Bible is a God who sets captives free. He interrupted Moses in the middle of his working life, and said to him, go to the biggest slave owner of the day, go to Pharaoh and tell him God said 'let my people go'."
The Labour Party Conference Service was also dedicated to IJM's Freedom Sunday.
Westlake told Premier what needs prayer: "There are investigators today around the world getting tooled up with undercover cameras and audio going into incredibly dangerous situations to gather evidence so that rescues can happen. They need protection.
"We've got aftercare workers trying to unlock a damaged little girl's heart because she has been abused day after day after day in captivity. That aftercare worker needs discernment and words of wisdom and words of knowledge."
He also encouraged Christians to contact UK companies and urge them to be more informed about their supply chain as "77 per cent of UK companies think that slavery is somewhere in their supply chain".
"They think we care about the price, and the style and the quality. Something churches can do is to help those brands we love know that we care about slavery, we care that the people making our clothes, processing our food, are treated well and are free," he added.
IJM's Freedom Sunday is growing exponentially, last year saw a 500 per cent increase in churches joining in from the previous year.
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