British police have arrested 14 men and women on suspicion of human trafficking and modern slavery offences in London.

Authorities raided five nail salons in south London in the early hours of Thursday after a five-month investigation amid fears that vulnerable people were employed at the venues.

Twenty-four people, including five children, found at the addresses were taken to a nearby reception centre to receive medical care and support.

It is unclear where they were from but there was a suggestion from authorities that some may be Vietnamese.

“Human trafficking, modern slavery and sexual exploitation often occur in plain sight," said Det Chief Insp Mark Rogers, from London's police force.

"And it is often the case that those carrying out these offences exploit those from less fortunate backgrounds who have travelled to our county for a better life.

"They prey on the knowledge that these individuals will carry out hard, labour-intensive work to provide for themselves."

The operation involved about 100 officers from immigration services, the local council, social services, the National Health Service and charities.

"Our primary concern is the safety and well-being of the women, children and other vulnerable adults caught up in this despicable trade," local councillor Victoria Mills said.

"Our officers are working with the police, specialist Vietnamese charities, the Salvation Army, social care and other support staff, to help those who wish to access support."

In October, 39 Vietnamese people were found dead in a refrigerated lorry in Essex. It is believed they travelled to the UK for work.