The police in the UK arrested a couple for keeping a man in his shack for four years as a slave. They are said to have forced Poles to work in exchange for food, the authorities said.

The 56-year-old woman and the 54-year-old man from Chilworth in southern England are being investigated on suspicion of modern slavery, the Gangmasters and Labor Abuse Authority (GLAA) said. The two suspects are again at large.

The investigators became aware of the case when doctors alerted the authorities. According to the GLAA, the alleged victim told health center employees he needed to work for food. He also slept on a plastic couch, did not have a flush toilet, and was given expired food.

"In the 21st century, nobody should be forced to live in such degrading and disgusting conditions," said Tony Byrne of the GLAA. Again and again, immigrants are lured to Britain with false promises and then have to work under precarious conditions.

In 2017, the number of reported cases of modern slavery and human trafficking had increased significantly in the UK. More than 5,000 potential victims have been notified by the National Crime Agency (NCA) authorities last year.