In a statement, the presidential office said Lula, 78, will now participate in the BRICS meeting via videoconference. He was initially scheduled to depart at 5pm on Sunday.
Lula's doctor, Roberto Kalil, said in an interview with GloboNews TV channel that the president suffered a fall that caused "great" trauma to the back of his head, requiring stitches for the injury and resulting in a "small brain haemorrhage" in the temporal-frontal region.
"It's a condition that will require repeat tests throughout the week. Any brain haemorrhage, theoretically, can worsen in the following days, so observation is important," he said.
Kalil added that Lula is doing well and can engage in normal activities.
According to a medical report issued earlier on Sunday by the Sirio Libanes Hospital in Brasilia, Lula suffered a laceration to the "occipital region" in the back of his head on Saturday.
The report said Lula "was advised to avoid long-distance air travel but is otherwise able to carry out his regular duties".
The government said in a post on X that Foreign Minister Mauro Vieira has been designated to lead the Brazilian delegation in the BRICS summit, departing later on Sunday.
The diplomatic forum founded 15 years ago by major emerging markets Brazil, Russia, India, China has since expanding to include South Africa, Egypt, Ethiopia, Iran and the United Arab Emirates.
Congresswoman Gleisi Hoffmann, president of Lula's Workers Party, posted on social media that she had spoken with the president and that "he is doing very well, just avoiding a long trip".
