Eight princesses from Abu Dhabi's royal family are guilty of treating more than 20 domestic workers in Brussels like "slaves" a decade ago, according to a Belgian court ruling.

The women, tried in absentia, each suspended sentences of 15 months in jail and fines of 165,000 euros ($184,350) each. Half of the fined amounts are due immediately, the rest when the guilty return to Belgium, said the judge.

Belgian prosecutors had sought 18-month prison sentences and nearly 1.9 million euros (2.1 million dollars) total in fines.

Some of the money will go to the victims for damages, with payments ranging from 1,800 euros to 5,000 euros. Prosecutors have not ruled out an appeal to seek more in damages.

"The princesses were, in effect, the employers of our clients," said Jean-Pierre Jacques, who represented some of the workers. But he said he and others representing the workers were happy that the court determined "that this was about a form of modern slavery."

The women - the widow of a sheikh and seven of her daughters - were found guilty of human trafficking and treating the workers in a "degrading way" during a 2007-08 stay in a Brussels luxury hotel. The verdict was 95 pages long and took the judge more than an hour to read.

However, the judges threw out charges of inhumane treatment and noted that no violations of Belgian labor law could be found, since the members of the UAE royalty were not the direct employers of the workers.

Prosecutors had argued that Princess Hamda Alnehayan, the widow of the sheikh of Abu Dhabi, and her daughters had confiscated the passports of their employees and refused to pay their salaries.

Following a tip-off, Belgian police had raided a luxury hotel, where the princesses occupied an entire floor for a year.

The domestic workers are reportedly from the Philippines, Morocco, India, Egypt, Turkey, Iraq and Syria, and were allegedly held captive for eight months.

During the court proceedings in May, lawyers said that the workers, who had been hired as nannies, cooks and domestic helpers, had to be at the princesses' disposal day and night, and were never allowed to leave the property.

The princesses' lawyer had called for acquittals, arguing that a company called Private Department arranged the employment contracts and it was therefore the company - not the princesses - that was legally responsible for breaches of the agreements. The judge did not take account of the fact that some members of the UAE royal family are listed as owners of Private Department.

But lawyers for the domestic workers pointed out that members of the sheikh's family, including some of the defendants, were registered as the company's owners.