British immigration officers have raided nearly 300 nail salons and arrested 97 people, mostly from Vietnam, for suspected immigration offences as part of a drive to tackle modern slavery, the Home Office said on Wednesday.

"Operation Magnify", a week-long operation concluded earlier this month, was a cross-government drive to stamp out illegal working by targeting specific "risk" industries, said the Home Office, Britain's interior ministry, in a statement. 

"This operation sends a strong message to those employers who ruthlessly seek to exploit vulnerable people and wilfully abuse our immigration laws," Immigration Minister Robert Goodwill, added.

"Modern slavery is a barbaric crime which destroys the lives of some of the most vulnerable in our society."

More than a dozen vulnerable people working in nail salons were found to have been at risk of modern slavery, said the statement while 68 businesses could face financial penalties of up to 20,000 pounds ($24,500) per illegal worker found.

The majority of the arrests made were Vietnamese nationals, but also included suspected immigration offenders from Mongolia, Ghana, China, Nigeria, Pakistan and India.

As interior minister, Theresa May put forward the "Modern Slavery Act" in 2015 and one of her earliest acts on taking office as Prime Minister in July was to pledge greater funding and establish a government task force on modern slavery.

Nearly 46 million people are enslaved globally, according to the 2016 Global Slavery Index, which estimated there were 11,700 victims living in Britain.

Those who are potential victims of trafficking will be offered support while those who have no right to be in the UK will be removed, the statement said.