Ricardo dos Santos knocked 11-time world champion surfer Kelly Slater out of a competition in 2012. Photo: AFP

Mr dos Santos, 24, was shot dead by an off-duty policeman outside his home.

He was shot three times when he confronted the officer and another man.

Mr dos Santos gained prominence after knocking 11-time world champion surfer Kelly Slater out of an event in 2012. He was known as a daring tube rider who had won international surfing awards.

He underwent four operations after being shot on Monday before dying in hospital on Tuesday afternoon.

There are conflicting reports on why Mr dos Santos was shot by the police officer.

A witness reportedly said that Mr dos Santos had asked the men to leave after spotting them using drugs and playing loud music on the beach outside his home, near the southern city of Florianopolis.

Other reports say he was shot while discussing a car they had parked at his property.

The officer involved in the incident says he acted in self-defence. He has been detained, but has not yet been charged.

'Senseless'

Kelly Slater called Mr dos Santos's death a "truly a senseless loss of life".

"Lack of education, poverty, and drugs don't make for a good mix and make life challenging in this country [Brazil], one of the most beautiful and scariest places I've been," he wrote on his Instagram page.

"Condolences to Ricardo's friends and family around the world. Our small community has lost another way too soon."

World champion surfer Gabriel Medina Pinto from Brazil also posted his condolences on Instagram.

"Ricardinho, you didn't deserve this!," he wrote. "Why does this kind of thing happen to good people?" he asked.

US champion surfer Brett Simpson wrote: "RIP Ricardo. Way too young, but you sure made an impact on so so many lives!".

South African surfer Travis Logie, who won the ISA World Surfing Games in 2002, tweeted: "Gonna miss watching you charge brother! Rest in Peace Ricardo".