Despite calls for life sentences from the prosecution, Etienne Nzabonimana was sentenced to 12 years behind bars while his half-brother Samuel Ndashyikirwa was given a 10-year term.
Under a 1993 law, Belgian courts can judge suspects accused of war crimes, crimes against humanity and genocide, regardless of where the alleged acts were committed or the nationality of the accused or victims.
Lawyers for the two, who denied the charges, asked for lenient sentences because four other Rwandans who were tried in similar circumstances but were more deeply implicated had not received life terms.
The sentences were handed down in Brussels a day after Nzabonimana was found guilty of 56 out of 57 charges against him. Ndashyikirwa was found guilty of 23 of the 24 charges he faced.
The charges included war crimes and murders committed in the Kibungo region of southeast Rwanda where 50,000 people were massacred in April 1994.
“They are relatively light sentences,” said Luc Walleyn, a lawyer for the civil plaintiffs, adding that the three judges and jury had clearly taken into account the fact that the men were among many others involved in the atrocities.
Dozens of Rwandans testified in the trial of the men, who were arrested in Belgium in 2002.
Witnesses said the two Hutu businessmen “supervised” several attacks, including one on a market, and others on churches. Several hundred people were killed, many with machetes, grenades and rifles.
Nzabonimana claimed that he never left his house during the Kibungo massacre.
He told the court that he had “no, no, no role in this tragedy”.
Ndashyikirwa while denying culpability, did express regret over his inability to save friends and neighbours from the massacre.
The six-week trial followed a 10-year investigation by the authorities in Belgium, which was the colonial power in Rwanda before it achieved independence in 1962.
The United Nations estimates 800,000 mainly Tutsis and moderate Hutus were killed in Rwanda in 1994.
In June 2001 a Belgian court jailed four Rwandans, including two nuns, for between 12 and 20 years for their roles in the massacres.