Billionaire philanthropist and Microsoft founder Bill Gates had his hands full on-stage in Beijing on Tuesday, showing a jar of human faeces.

The stunt was part of his speech at the Reinvented Toilet Expo event – a showcase for new toilet technologies.

The Bill & Melinda Gates Foundation has spent more than $200m on researching the field across the last seven years.

Twenty cutting-edge sanitation products were on display, intended to destroy harmful bacteria and prevent disease.

“I have to say, a decade ago I never imagined that I’d know so much about poop,” Mr Gates joked at the conference. “And I definitely never thought that Melinda would have to tell me to stop talking about toilets and faecal sludge at the dinner table.”

The entrepreneur was helping to launch the three-day event in China – where leader Xi Jinping has made a so-called “toilet revolution” across the country a policy priority.

The showcased products aim to revolutionise sanitation technology by operating off-grid to separate liquid and solid waste and remove harmful by-products.

“It’s no longer a question of if we can reinvent the toilet and other sanitation systems,” he said. “It’s a question of how quickly this new category of off-grid solutions will scale.”

The entrepreneur described the inventions on display as the “most significant advances in sanitation in nearly 200 years”.