A Chinese chef was forced to sleep in a filthy cage in an Amsterdam restaurant for a year while working in slave-like conditions, Dutch prosecutors said.

The cook was "exploited in the most terrible way", according to court documents seen by AFP on Thursday relating to the ongoing trial of a 52-year-old female Chinese restaurant owner and four other suspects on human trafficking charges.

"The victim was intimidated and had to work under miserable conditions," while being shuttled back-and-forth between Chinese restaurants in Amsterdam and the eastern city of Arnhem.

"The man... was not allowed to visit a doctor and had to sleep in a cage in an Amsterdam restaurant under video surveillance. He spent the last year in this stinking cage, haunted by the memory of a beating he received," prosecutors said.

The unnamed man had to work long hours for almost no pay "while his bank account was raided by the suspects," they added.

"For months he sat in a foreign country, with no money and not being able to speak the language. This case is about an incredibly lonely, exploited and desperate man."

Prosecutors are seeking a 20-month sentence against the restaurant owner and sentences of between 10 to 15 months for the other four.

The Chinese chef, whose age was not released, travelled to the Netherlands in late 2007 to work in Chinese restaurant kitchens.

Human trafficking has been on the rise in the Netherlands in recent years, official statistics show, with 605 cases registered in 2011. Last year's figures are not yet available.

Many victims in the Netherlands are women brought to work in the sex industry, but exploitation in the broader labour market is also on the rise, according to Dutch anti-human trafficking organisation CoMensha.