A Swiss court on Friday found members of Britain’s wealthiest family guilty of exploiting domestic workers at a luxury villa in Geneva, but acquitted them of the more serious charge of human trafficking.

Prosecutors had charged four members of the family — Prakash Hinduja; his wife, Kamal Hinduja; their son Ajay Hinduja; and their daughter-in-law Namrata Hinduja — with trafficking and exploiting several workers from India.

They were accused of confiscating the employees’ passports and forcing them to work 16 hours a day or longer without overtime pay in the villa. Lawyers representing the Hindujas had denied the allegations.

The court on Friday sentenced Prakash and Kamal Hinduja to four years and six months in prison, and Ajay and Namrata Hinduja to four years, according to news agencies. It also ordered them to pay about $950,000 in compensation, as well as about $300,000 in procedural fees. Najib Ziazi, a business adviser for the family who also faced charges, was found complicit in the exploitation.

The Hinduja family leads a multinational conglomerate with large holdings in automotive manufacturing, banking, oil and gas, real estate and health care. The Sunday Times of London recently estimated the family’s net worth at 37 billion pounds, or $47 billion, and listed the Hindujas as Britain’s richest family.

Arguments in the closely watched trial began on June 10, with the lead prosecutor, Yves Bertossa, claiming that the family had budgeted more for a pet than it had for the salary of one domestic worker, according to reports in the Swiss news media.

Some domestic workers, who took care of children or housework, were paid as little as 10,000 rupees a month (about $120 currently), according to the indictment. Many of the workers were from poor backgrounds in India, it said, and had toiled “from dawn until late in the evening” without overtime pay.

Their salaries — well below Geneva’s minimum wage for domestic workers — were paid into Indian bank accounts that they could not easily get access to, the indictment said.

Prosecutors had alleged that the Hinduja family had confiscated the domestics workers’ passports and told them not to leave the villa, where they slept in bunk beds in a windowless basement room. The workers were expected to be available at all times, the indictment said, including on trips to France and Monaco, where they toiled under the same conditions.

Romain Jordan, a lawyer representing the Hinduja family, rejected what he called the “exaggerated and biased allegations.”

“The members of the Hinduja family vigorously deny these allegations and remain determined to defend themselves,” he said in a statement before the verdict. Mr. Jordan did not immediately respond to a email requesting comment after the judgment.

A civil case involving the main accusers, who worked for the family, was settled last week, according to Swiss news reports. Mr. Jordan declined to discuss the terms, but said that the agreement was “confidential” and that the plaintiffs had withdrawn their complaints.

In the criminal case, prosecutors had sought prison sentences of up to five and a half years, along with millions of francs in fines and compensation, according to the Swiss news media.

Three Hinduja brothers lead the family’s conglomerate, with two based in Britain and around Europe. The family owns extensive real estate in London, including a 25-bedroom residence and a five-star Raffles Hotel in a historic former government building, the Old War Office.

The most senior of the brothers, Srichand P. Hinduja, who was also joint chairman of the Hinduja Group, died in May last year at 87. Before his death, factions of the family had been involved in a protracted battle over the control of family assets.