PORTLAND, Ore. -- All-Star guard Brandon Roy has told Portland he plans on retiring because of ongoing trouble with his knees.

A five-year veteran who helped the team shed its "Jail Blazers" reputation, Roy has been dogged by pain for the past two seasons. He has said in the past that he lacks cartilage between the bones in both knees.

"This is a very difficult and painful day," Roy said in a statement released by the team. "I love the game, I love the Portland Trail Blazers and I love our fans, but after consulting with my doctors, I will seek a determination that I've suffered a career ending injury, pursuant to the rules of the collective bargaining agreement."

Acting general manager Chad Buchanan said the Trail Blazers were still looking at their options concerning Roy, including the amnesty clause in the NBA's new labor agreement.

"My family and health are most important to me and in the end this decision was about them and my quality of life," Roy said in the joint statement released by the team. "I want to thank (owner) Paul Allen, (team president) Larry Miller, Coach (Nate) McMillan, the entire Trail Blazers organization and our fans for all of their love and support during my time in Portland. It was a great ride."

Players were informed of Roy's surprising decision on Friday morning before the team's first practice of training camp.

"I couldn't believe it," Blazers forward Nicolas Batum said. "I still can't believe it."

Roy did not report to the Blazers' practice facility on Friday and his agent did not respond to a request for comment on any retirement plans. ESPN The Magazine's Chris Broussard and ESPN.com's Chad Ford first reported Roy's decision.

Allen said he had been excited at the prospect of seeing Roy back on the court in training camp.

"Like every Blazer fan, I am very sad to learn that Brandon's playing days have ended," Allen said in the statement released by the team. "Up until Thursday night we were looking forward to seeing him back on the court Friday for the first day of practice.

"I want to personally thank Brandon for all he's done as a Trail Blazer, on and off the court. He is a true All-Star and we all rooted for him as he gave us so many amazing moments during his five years as a Blazer."

NBA spokesman Tim Frank said Roy had not yet filed the appropriate paperwork with the league.

McMillan spoke to Roy on Thursday night and described him as disappointed.

"Of course, we know what he means to this franchise. He was part of bringing it back, bringing back winning basketball," McMillan said. "Unbelievable talent. You're sad to see a situation like this happen."

It sounded as if Roy was ready to go when Miller, Buchanan and McMillan held a news conference Monday. Roy had met with team officials earlier that day and said he felt good and was ready to help the team in any way he could.

But it became apparent during a medical evaluation Thursday that Roy's knees were not going to be able to handle another season.

"It's a tough situation," Blazers center Marcus Camby said. "People will say, 'Hey, he'll get his money.' But Brandon's a competitor."

Buchanan said late Friday that the team was exploring its options concerning both a formal medical retirement and amnesty for Roy, who signed a five-year maximum contract with the team in 2009. The clause would allow the team to waive Roy without having his salary count against the cap and luxury tax.

"We're somewhat in the infant stages of going through that process and getting that started," Buchanan said. "But (we're) very supportive of Brandon in all of this. It's a very difficult decision as you can imagine."

If the 27-year-old Roy files for medical retirement, insurance likely would take care of his salary in coming years. His salary would not count against the cap after one year.

Roy, who averaged 19 points, 4.7 assists and 4.3 rebounds for his career, sat for stretches of last season because of soreness. He had arthroscopic surgery on both knees last January and finished the season with a career-low average of 12.2 points in 47 games.

"Brandon Roy will always be a Trail Blazer in our hearts and minds," Miller said in the statement. "He was an All-Star and a warrior every night that he stepped on the court and gave everything he had to help us win. He was a role model on and off the court, and through his leadership he turned us into a winning franchise once again."

The sixth overall pick in the 2006 draft out of Washington, Roy was acquired by the Blazers in a draft-day trade. The 2007 NBA Rookie of the Year made the All-Star team from 2008-2010.

Nicknamed "The Natural" by the team's broadcasters, Roy has been the affable face of the franchise and remains popular among Portland fans.

In last season's first-round playoff series against the eventual NBA champion Dallas Mavericks, Roy shook off the pain and led Portland to a stunning 84-82 comeback victory in Game 4. He scored 18 of his 24 points in the fourth quarter as the Blazers erased a 23-point deficit.

But when it was over, Roy sounded defeated.

"This has just been a tough year, my most difficult as a Blazer," he said. "I tried to make the most of things. I can definitely say I honestly tried. I've given this team my best."

On Friday, Camby pointed up to the retired jerseys lining the rafters of the Blazers' practice facility.

"His number belongs up there," Camby said. "That's all I can say."

Information from ESPN.com's Chad Ford and Marc Stein, and The Associated Press was used in this report.