Dale Earnhardt, the greatest stock car star of his era, was killed in a crash on the last turn of the last lap of the Daytona 500 as he tried to protect the victory of a teammate.

The 49-year-old driver had to be cut from his battered car Sunday and was pronounced dead of head injuries at hospital.

"He had what I felt were life-ending type injuries at the time of impact and nothing could be done for him," said Dr Steve Bohannon, an emergency physician at the hospital who also works for Daytona International Speedway.

The accident happened a kilometre from the finish of the NASCAR season-opener as Earnhardt's newest driver, Michael Waltrip, and son Dale Earnhardt Jnr were in front racing toward what should have been the most triumphant moment in the brief history of Dale Earnhardt Inc.

Earnhardt, a master of superspeedway racing, was fighting for third place, leading a tightly bunched five-car pack heading through the final turn. The back left corner of his famed black No 3 Chevrolet was bumped by Sterling Marlin.

Earnhardt's car fishtailed slightly and briefly slid to its left, down toward the infield, before suddenly swinging back to the right and cutting across traffic at a sharp angle. He clipped Ken Schrader, whose yellow Pontiac carried both cars hard into the concrete wall headfirst at about 290 kph.

With Earnhardt's car already smoking and shredding at the front, Schrader's car stayed lodged into the passenger's side of the Chevrolet, forming a T. The cars careened again off the wall, ploughing into the final turn and sliding to a stop on the infield grass.

"I guess someone got into Dale because Dale got into me and then we went up," Schrader said. "We hit pretty hard and Dale hit harder."

The scene was grim as safety workers removed Earnhardt from the car, and the accident removed all the luster from a glittering race that kept the record crowd of 195 000 spectators on their feet most of the afternoon.

Many of them were well on their way home when NASCAR president Mike Helton made the announcement, about 90 minutes after the race ended.

"This is undoubtedly one of the toughest announcements I have ever personally had to make. We've lost Dale Earnhardt," Helton said.

Fans in and around the sprawling speedway wept after hearing the news. The track lowered its huge American flag in the infield to half-staff after the race.

Earnhardt was a seven-time Winston Cup champion, and his 76 victories were the most among active drivers. He continued to race for longtime friend and boss Richard Childress while starting his own team, which expanded to three cars with the addition of Waltrip this year. His other drivers were Dale Jr. and Steve Park.

The death of Earnhardt left NASCAR reeling in the wake of a 2000 season in which three of its young stars were killed in separate accidents.

Adam Petty, the fourth generation of stock car racing's most famous family, and Kenny Irwin died in crashes two months apart at New Hampshire International Speedway and Tony Roper was killed later in the year in a crash during a truck race at Texas Motor Speedway. All three died of the same type of head injuries that apparently killed Earnhardt.

Following those deaths, safety had become a front-burner issue for the sport, with a debate over possible rules changes and the use of new safety equipment.

Earnhardt wore an open-faced helmet and shunned some of NASCAR's other basic safety innovations. He didn't like the restrictor plates NASCAR used to slow speeds at its fastest tracks, and refused to wear a Head And Neck Safety (HANS) brace that recently has been touted as a way to help prevent serious head injuries.

Dr Steve Bohannon said Earnhardt probably died of severe head injuries, particularly to the base of the skull. They were the same type of injuries that killed the three drivers last year.

"I know the full-face helmet wouldn't have made a difference," Bohannon said. "I don't know if the HANS device would have helped. I suspect not."

Earnhardt's death completely overshadowed the victory by Waltrip, his first in 15 years and 463 races on Winston Cup circuit.

At first, Waltrip, the younger brother of retired three-time champion Darrell Waltrip, was jubilant, scrambling from his car in Victory Lane and shouting in a raspy voice: "This is the Daytona 500, and I won it! I won the Daytona 500! I can't believe it!"

But he was sombre as it became apparent that his new boss was badly injured.

"The only reason I won this race is Dale Earnhardt," Waltrip said. Sapa-AP