The U.N. Human Rights Committee said it had information to suggest Oleg Grishkovtsov and Andrei Burdyko were executed in Belarus as early as July 13. Both men allegedly were tortured and denied a free trial and their cases were under consideration by the United Nations.
"The committee deplores the fact that, by proceeding to execute these two individuals, Belarus has committed a grave breach of its obligations under the Optional Protocol to the International Covenant on Civil and Political Rights," committee Chairwoman Zonke Majodina said in a statement.
Majodina said that while the protocol doesn't specifically prohibit the death penalty, nor is Belarus party to the measure, capital punishment must be carried out with respect to international benchmarks for justice.
Grishkovtsov and Burdyko were found guilty of murder, assault, arson, kidnapping and robbery.
The human rights committee said it expressed its concern to Belarus last week and hasn't received a reply. It's the second time Belarus executed individuals who were under consideration by the rights committee.
Nearly 400 people were arrested during Independence Day celebrations in Belarus in early July.
Washington and its European allies hit Minsk with sanctions after President Alexander Lukashenko rounded up hundreds of his political opponents following elections earlier this year.