He said LGBTs were "not natural" for biological reasons.
"Men marrying men, women marrying women... It's not natural. Just imagine if we all indulge in that. No children. One generation and the whole human race is wiped out," Mahathir said.
Speaking at a forum "Politics and Business: The Malaysian Connection" here, Mahathir said that once you catered for a specific group such as the LGBT, others would follow suit and ask for more rights too.
"Now we have institutions for men and men, women and women. I want to see how many children they have," he said.
In Muslim majority Malaysia LGBT rights are not recognized. The nation retains its colonial era penal code criminalising sodomy.
