A gang of eight who turned human trafficking into "a lucrative family business" were jailed on Thursday for more than 24 years, amid a major British crackdown on modern day slavery.

Frantisek Cisar, 37, leader of the gang which forced vulnerable Slovakians to work for as little as £4 a day, was jailed for nine years. Five family members and two others were jailed for up to four-and-a-half years each.

Police said the Cisar family lured their victims to the north of England from Slovakia with the promise of a better life, often targeting people in extreme poverty.

But when their victims arrived, they had to renovate and clean properties for "pitiful wages", with one person earning just £3,000 in more than three years, prosecutors at Leeds Crown Court said.

"The (Cisars) lived comfortably off the forced labour of others, who they deliberately targeted knowing their victims were desperate to improve their lives," said Senior Crown Prosecutor David Holderness.

Their victims were "living in a nightmare", working for next to nothing, housed in very poor conditions and isolated by their lack of English, he added.

Britain has been seen as a world leader in the fight against human trafficking since passing the 2015 Modern Slavery Act.

Police said 37 people, aged one to 57, were rescued during the operation.

The family controlled their victims' bank accounts and kept their wages, while also claiming benefits in their names.

"These people were involved in modern day slavery - a crime that trades in human misery," said Detective Superintendent Pat Twiggs of West Yorkshire Police. "Today's sentences should send out a clear warning that it will not be tolerated."

In a separate landmark case on Thursday, a drug trafficker who used children aged 14 and 15 to deal crack cocaine and heroin in central England was sentenced to 14 years.

Prosecutors believe Zakaria Mohammed, 21, is the first person to be jailed under modern slavery laws for trafficking children.

The two cases come a day after specialist officers in the north of England rescued another potential slavery victim who had lived in a six-foot shed for 40 years. A 79-year-old man was arrested on suspicion of modern slavery offences.

Investigator Martin Plimmer told the BBC broadcaster that the 58-year-old victim was thought to have worked without pay since his teens.

The shed had just a soiled duvet on the floor.

"It was conditions that no human being should live in," Plimmer said. "It's an extremely sad and serious case."