LONDON - Three women enslaved for 30 years have been rescued from a house in London including one who has spent her entire life in domestic servitude, police said on Thursday.

Officers, who arrested a man and a woman, both 67, at their south London home, described it as the worst case of servitude to have emerged in the British capital.

Police said they did not believe the women - a 69-year-old Malaysian, a 57-year-old from Ireland and a 30-year-old Briton - were related and there was no evidence of sexual abuse. It was not clear where the youngest of the three was born.

The women appeared to have had limited freedom over the years but it was not until one victim summoned the courage to call a charity on October 18 after watching a BBC documentary featuring an anti-slavery campaigner that they came to light.

After building trust with workers at Freedom Charity, the two younger women met with charity staff and police on October 25 and led them to the house where they rescued the third woman and all three were taken to safety.

The case was kept secret until Thursday's arrests of two people described as non-British nationals on suspicion of being involved in forced labour and domestic servitude. The man and woman remain in custody.

"These women are highly traumatised, having been held in servitude for at least 30 years with no real exposure to the outside world, and, trying to find out exactly what has happened over three decades will understandably take some time," Detective Inspector Kevin Hyland said in a statement.

"Our unit deals with many cases every year but has never unearthed such a staggering example of people held against their will for their whole lifetime."

He added this was not a common case in Britain but urged anyone else in similar circumstances to come forward.

The fate of the women evoked memories of lengthy abductions in the United States and Austria.

Hyland said the trail to the women began on October 21 when the Freedom Charity reported a call to police from a woman who said she had been held against her will in the house for more than 30 years after the organisation featured in the documentary.

"The relationship between the women is part of an ongoing investigation and we are not willing to speculate.  However, we believe that the 30-year-old woman had been in servitude all her life," he said.

Aneeta Prem, the founder of Freedom Charity that works on issues including forced marriage, said it took a lot of courage for the women to come forward as they were terrified.

"They had been trying for a number of years to work out a way to leave," Prem said, declining to give details on the location of the house. "People will be shocked this can happen in the UK and in a capital city like London."

She added that neighbours had not reported noticing anything untoward happening at the property that was "an ordinary house in an ordinary street".

The women were doing "remarkably well" physically and mentally under the circumstances, Prem said. "This will be a very long haul for them to try to return to a normal life."

In the United States, former bus driver Ariel Castro was convicted in August of the abduction, torture and decade-long confinement of three women. He was found hanged in his cell at an Ohio prison in September.

That followed two infamous cases in Austria.

Natascha Kampusch was found in 2006 after being kidnapped at the age of 10 by Wolfgang Priklopil and held captive for eight years. In 2009, Josef Fritzl was sentenced to life in prison after keeping his daughter Elisabeth captive in a cellar for 24 years and fathering seven children with her.

Last month, the first Global Slavery Index revealed there were nearly 30 million people living as slaves in 162 countries and that Britain was not immune to the problem.

Although ranked 160th on the list, there were still estimated to be more than 4,000 slaves in Britain, an estimate that the index judged to be conservative.