According to local news outlets, the last sighting of him was when he cast a ballot in the national election on May 13. He appeared upbeat and walked without assistance, and briefly addressed reporters in southern Davao City.
Salvador Panelo, the president's spokesman, told reporters Monday that he had spoken with Duterte by phone and that the president was at his official residence "signing papers."
"I talked to him yesterday," he said. "His voice was very strong." Panelo added that Duterte laughed off the rumours that he was in the hospital.
"In other words, to him, it's not a serious matter," the spokesman said. "Because if it was serious, he always tells the public about it."
Panelo said Duterte has been in Manila since Friday, and has spent the past two days with his family. Panelo said that when he asked the president about the rumours of a hospital visit, Duterte told him: "I neither confirm nor deny. You draw your own conclusions."
Reports of poor health have followed Duterte for some time. He revealed in October that he made a secret visit to the hospital earlier that year for an endoscopy and colonoscopy.
The tests, according to the presidential palace, were routine as the leader suffers from Barrett's oesophagus — a condition where cells grow abnormally in the oesophagus and can sometimes develop into cancer.
Duterte is known to see doctors at the Cardinal Santos Medical Center in Manila, and some news outlets speculated that he was being treated there most recently after patients were quoted by local radio as saying the security there had been unusually tight over the weekend.
A change in Duterte's complexion, which has noticeably darkened, has also fueled speculation of illness, though Duterte dismissed it as sunburn and the natural discolouration of ageing.
According to Rappler, a local news outlet that has been monitoring Duterte's public appearances, he has been suddenly absent from the public eye without an explanation, at least four other times.
There were rumours earlier this month that Duterte was ill when he took several days off after an official visit to China, disappearing from April 29 until May 4. Twice in June 2017 he went unseen for several days, and once in February of that year.
Written by: Jason Gutierrez and Megan Specia
© 2019 THE NEW YORK TIMES