Theresa May will promise a "radical approach" and "tireless" work to eradicate slavery in a service at Westminster Abbey on Wednesday to commemorate the work of William Wilberforce.

The Home Office estimates there are between 10,000 and 13,000 victims of human trafficking in the UK with the global figures around 45 million. The UK's anti-slavery commissioner Kevin Hyland said these cases were due to "chronic weaknesses" within law enforcement.

"Inadequacies in this area impact not only present and future victims, but could also allow organised crime groups to act with impunity, compromising the UK's national security," Hyland said.

The Prime Minister will address the congregation at the special service in honour of Wilberforce, an 18th-century Christian anti-slavery campaigner, on Wednesday evening. She will say: "Our challenge is to ensure that the fight against slavery carries on – to free people from the bonds of servitude, to free those in mental chains, and to free people from the clutches of slave-drivers and traffickers.

"I want Britain at the forefront of this fight, leading the world with our efforts to stamp out modern slavery."

She will promise £33m from the UK's aid budget for countries where victims are regularly trafficked to Britain such as Nigeria, Vietnam, Romania, Poland and Albania.

"We will work tirelessly, relentlessly pursuing the perpetrators of these appalling crimes so that victims of slavery can go free," May will say.

Here are 10 quotes to remember Wilberforce, whose anti-slavery efforts led to the Abolition of the Slave Trade Act in 1807:

1. "You may choose to look the other way but you can never say again that you did not know."

2. "We are too young to realise that certain things are impossible... So we will do them anyway."

3. "If to be feelingly alive to the sufferings of my fellow-creatures is to be a fanatic, I am one of the most incurable fanatics ever permitted to be at large."

4. "True Christians consider themselves not as satisfying some rigorous creditor, but as discharging a debt of gratitude"

5. "Let him then, who would be indeed a Christian, watch over his ways and over his heart with unceasing circumspection. Let him endeavour to learn, both from men and books, particularly from the lives of eminent Christians, what methods have been actually found most effectual for the conquest of every particular vice, and for improvement in every branch of holiness."

6. "God Almighty has set before me two Great Objects: the supression of the Slave Trade and the Reformation of Manners."

7. "It makes no sense to take the name of Christian and not cling to Christ. Jesus is not some magic charm to wear like a piece of jewellery we think will give us good luck. He is the Lord. His name is to be written on our hearts in such a powerful way that it creates within us a profound experience of His peace and a heart that is filled with His praise."

8. "Some might say that one's faith is a private matter and should not be spoken of so publicly. They might assert this in public, but what do they really think in their hearts? The fact is, those who say such things usually don't even have a concern for faith in the privacy of their interior lives."

9. "What a difference it would be if our system of morality were based on the Bible instead of the standards devised by cultural Christians."

10. "In the calmness of the morning before the mind is heated and weary by the turmoil of the day, you have a season of unusual importance for communing with God and with yourself."