According to the news agency, Makej died quickly. The cause of death has not been given.
Makej has been foreign minister since August 2012, and was scheduled to meet his Russian counterpart Sergei Lavrov on Monday, reports Reuters.
“We are shocked by the information,” Maria Zacharova, spokeswoman for the Russian Foreign Ministry, announced on the messaging app Telegram.
During Makej’s time in office, Belarus has been repeatedly criticized by the West, including for allowing Russian forces to be based there during the war in Ukraine.
In September, Makej defended Belarus’ position before the UN Security Council.
– We have said and continue to say: Belarus has never advocated war. But we are not traitors either. We have commitments to our allies, and we closely follow and will follow the spirit and … of the international treaties that we are part of, he said then.