Former slaves are best placed to support survivors, raise awareness and fight a crime estimated to affect 40 million people worldwide, said two women trafficked to Europe from Uganda and the Philippines with promises of work and education.

For Maria, who was trafficked from Uganda as a teenager and sold into prostitution in the Netherlands, support from a social worker helped her to gain legal documents and a masters degree which ultimately led to a job with charity the Salvation Army.

"We need to look beyond telling stories," Maria, who did give her real name, told the Thomson Reuters Foundation's Trust Conference on modern-day slavery at the European Parliament.

"We need to invest in survivors and let them act as a laboratory for ways to come up with policies," added Maria, who campaigns against slavery for the Salvation Army in Europe.

No data exists on the number of trafficking victims who are freed, rescued or escape but with modern slavery now regarded as a major global threat, countries and charities are ramping up efforts to catch slavemasters and provide support to survivors.

"The road to recovery can be long and hard," said Anne Read, head of modern slavery at the Salvation Army in Britain.

"(But) we have seen people who have experienced exploitation themselves working directly with our clients where the empathy they can bring to this work is incredibly powerful," she added.

SETTING AN EXAMPLE

For many survivors, freedom brings new challenges as they often suffer stigma, discrimination and trauma, and struggle to access counselling, healthcare and housing.

Yet providing former slaves with education, training and jobs can help them to rebuild their lives and set an example for others, said Minh Dang of the Survivor Alliance, a platform for victims to connect with each other and anti-slavery experts.

"Survivor leaders can give hope to those just starting their journeys in freedom, offering an example of what is possible in the future," added Dang, a survivor-turned-activist who was sold for sex by her family during her childhood in the United States.

From making clothes and furniture in India to cooking, catering and even coding in the United States, companies worldwide are increasingly looking to employ slavery survivors.

Major British companies plan to create 300 such jobs by 2020 as part of a scheme launched year by the supermarket Co-op that sees victims offered a four-week paid placement followed by a non-competitive interview - leading to a possible permanent job.

Such opportunities are vital to offer hope to victims who often go unseen and unheard, said Filipina ex-maid Zita Cabais, who moved to Paris to find work but was trapped in debt bondage by traffickers, and stripped of her passport by her employer.

She managed to contact the CFDT - one of France's biggest trade unions - and they helped Cabais escape the exploitation.

Cabais now works full-time for the union, fighting for the rights of domestic maids - many of whom are abused and enslaved.

"Many victims are not able to talk," she told the conference. "They are not able to give their voice."

"We are invisible. No one can see us. No one can identify us."