German special police pose at their Federal Police Offices in Potsdam, Germany, May 15, 2018.
Photo by Reuters/Hannibal Hanschke. 

Authorities in Germany confirmed they had busted a large-scale ring that smuggled 155 Vietnamese into the country and arrested six suspects. 

On Monday, over 700 German police officers raided over 30 homes, nail parlors and restaurants across the country in an expanded investigation into the human trafficking ring, carried out from June last year, Vietnamese News Agency reported.

The raids targeted 13 Vietnamese suspects, with six arrested Monday, federal police spokesman Axel Bernhardt said.

They were alleged to have smuggled at least 155 Vietnamese by road into Germany from other European countries and charged each migrant $5,000-$20,000, paid in Vietnam.

Smuggling occurred via travel, export-import and recruitment companies in Germany, Romania and Vietnam.

Many illegal immigrants ended up in nail parlors, restaurants or sweat shops to pay back their debts, police said.

The Vietnamese Embassy in Germany asked local authorities to provide the identities of all detained traffickers.

Vietnam has recorded over 3,400 victims of human trafficking since 2013, officials said at a conference in November last year. 

Last October, 39 Vietnamese were found dead in a refrigerated container truck in Essex in a human tragedy that shocked the world. Last month, British police wrapped up post-mortems, revealing the provisional cause of death to be a combination of hypoxia and hyperthermia.