It comes amid talks of forming a new coalition to govern the country.
Mahathir, 94, assumed office in May 2018 for his second stint as prime minister.
A spokesman from the prime minister’s office declined to comment, saying only that a statement will be issued soon, Reuters reported.
The sources declined to be named as they were not authorized to talk to the media.
Malaysian politics was in turmoil Monday after leader-in-waiting Anwar Ibrahim denounced a “betrayal” by coalition partners he said were trying to bring down the government, two years after it stormed to victory.
Anwar’s “Pact of Hope” alliance was thrown into crisis after his rivals within the coalition and opposition politicians met at the weekend reportedly to try to form a new government.
Speculation is mounting that Anwar, who had been the presumptive successor to Prime Minister Mahathir Mohamed, and his lawmakers would be left out of any new coalition, ending his hopes of becoming premier any time soon.