NASCAR star Tony Stewart says in his first public comments since striking and killing fellow driver Kevin Ward Jr. that the crash at an event in upstate New York will "affect my life forever."

Stewart, a three-time NASCAR champion, has not raced since his car hit Kevin Ward Jr. at an Aug. 9 sprint car event. Stewart pulled out of the NASCAR race at Watkins Glen the next morning, then skipped the races at Michigan and Bristol Motor Speedway.

"This is one of the toughest tragedies I've ever had to deal with," Stewart said Friday, speaking softly while reading from a sheet of paper. "This is something that will definitely affect my life forever. This is a sadness and a pain that I hope no one ever has to experience in their life.

"With that being said, the pain and the mourning that Kevin Ward's family is experiencing is something that I can't possibly imagine."

Stewart did not take questions from media, saying "there will be a day when I can sit here and answer the questions."

Stewart, who will return to NASCAR competition on Sunday night at Atlanta Motor Speedway after qualifying 12th on Friday, said "being back in car this week with my racing family will help me get through this difficult time."

Stewart-Haas Racing executive vice president Brett Frood said it was "100 per cent" Stewart's decision to race. He said Stewart is "emotional" but ready to return.

Stewart, who was described by police as "visibly shaken" the night of Ward's death, had been in seclusion ever since.

Before Friday, Stewart's only comment since Ward's death was a statement the day after the crash in which he said "there aren't words to describe the sadness I feel about the accident that took the life of Kevin Ward Jr."

Ward had climbed from his car after it had spun while racing for position with Stewart. The 20-year-old walked down onto the racing surface waving his arms in an apparent attempt to confront Stewart.

Authorities said the first car to pass Ward had to swerve to miss hitting him. The front of Stewart's car then appeared to clear Ward, but Ward was struck by the right rear tire and hurtled through the air. He died of blunt force trauma.

It was not clear if the 43-year-old NASCAR superstar will be charged in Ward's death. Ontario County Sheriff Philip Povero has said investigators did not have any evidence to support criminal intent by Stewart. Povero said this week he has no new updates on where the investigation stands.

NASCAR released a statement Thursday saying that Stewart was eligible to return because he "has received all necessary clearances required to return to all racing activities."

Ward's death prompts new safety rule

Stewart, who has 48 career Cup wins in 542 starts, is one of the biggest stars in the garage.

His peers have been protective of him as questions emerged in the aftermath of the crash, and it pained them that Stewart was grieving in private and had cut off communication with so many of them.

NASCAR rules state a driver must attempt to either qualify or race the car in every points-paying event to be eligible for the Chase for the Sprint Cup championship in two weeks, but Stewart was granted a waiver on Friday.

But with two weeks left until the Chase for the Sprint Cup championship, Stewart is preparing to go racing again. He rolled onto the track for a 90-minute practice session Friday afternoon, cheered by fans as his No. 14 Chevrolet exited the garage. It didn't take long to get back up to speed. Early on, he had the 17th-fastest time among the 44 drivers attempting to qualify, turning a lap of more than 187 miles per hour.

Stewart will be back for qualifying Friday evening, with the race set for Sunday night on the 1.54-mile trioval.

Not long after Stewart spoke to the media, NASCAR announced he would be eligible for the playoff if he wins either the Atlanta race or next week at Richmond, the final event before the 16-driver championship field is set.

Mike Helton, president of the governing body, said Stewart received a special waiver that normally applies to a driver who misses a race for medical reasons.

Helton said NASCAR made the decision after consulting with third-party experts who "were relevant under these circumstances." He would not elaborate.

"We want to join everybody in racing in welcoming Tony back," Helton said. "He's a great asset to NASCAR. He's a great champion, a great participant in our sport. It's great to have him back."

Since Ward's death, NASCAR has announced a rule that prohibits drivers from exiting from a crashed or disabled vehicle — unless it is on fire — until safety personnel arrive. Last week, Denny Hamlin crashed while leading at Bristol and stayed in his car until safety personnel arrived.

But Hamlin then exited his vehicle and angrily tossed a safety device at Kevin Harvick as he passed by moments later. He was not penalized.

Shortly before practice, Stewart chatted in the garage with fellow driver Kurt Busch. Another top driver, Denny Hamlin, said returning to the track should be good therapy for Stewart.

"From my standpoint, getting in a race car always makes whatever is going on outside in your life a little bit better," Hamlin said.

Asked if it was fair to make Stewart eligible for the Chase, Hamlin wavered a bit.

"I don't know. It's a very vague thing," he said. "It's tough to say what's considered medical and not. Either way, I'm fine with Tony. In or out, it's good with me."

With files from The Associated Press