NEW YORK (AP) — The NBA players' association plans to file a grievance against the Portland Trail Blazers, who have threatened litigation against any NBA club considering signing Darius Miles.

The former Trail Blazers forward is attempting a comeback — a potentially very expensive one for the Blazers — from major knee surgery.

If Miles plays in two more games this season, Portland would be on the hook for $18 million — the amount remaining on Miles' contract, which would count against Portland's salary cap and force the team to pay luxury tax.

"We are shocked at the brazen attempt by the Portland Trail Blazers to try to prevent Darius Miles from continuing his NBA career," players' association director Billy Hunter said in a statement.

"Their attempt to intimidate the other 29 NBA teams by threatening frivolous litigation merely for signing this capable NBA veteran is a clear violation of the anti-collusion and other provisions of our Collective Bargaining Agreement. We will vigorously defend Darius' rights."

Hours before Miles cleared waivers Friday, Portland team president Larry Miller sent an e-mail to the other 29 NBA teams warning of legal action if a team were to take Miles simply to adversely impact Portland's salary cap.

"Persons or entities involved in such conduct may be individually liable to the Portland Trail Blazers for tortuously interfering with the Portland Trail Blazers contract rights and perspective economic opportunities," Miller's e-mail reads, according to SI.com and Yahoo.com, which obtained it. "Please be aware that if a team engages in such conduct, the Portland Trail Blazers will take all necessary steps to safeguard its rights, including, without limitation, litigation."

As a result of Miller's e-mail, the issue was scheduled to be discussed Friday at a previously scheduled meeting between NBA and players' union attorneys.

"Under league rules, teams are free to sign Darius Miles to a Uniform Player Contract if they wish to secure his services as a player, and any such contract would be approved by the NBA," the league said in a memo sent to teams.

Miles' contract would become guaranteed for the rest of the season if he plays in 10 games. He already has played in eight games this season — six preseason games for the Boston Celtics, then two games for the Memphis Grizzlies before being released earlier his week.

The Trail Blazers did not immediately return messages left by The Associated Press seeking comment Friday. Miles' agent, Jeff Wechsler, could not be reached for comment.

Portland waived Miles, who has not played for the team since microfracture surgery on his right knee in November 2006, at the end of last season after determining he was medically unable to play.

Miles, the third overall pick by the Los Angeles Clippers in the 2000 NBA draft, was on the Blazers' roster from 2004-08. He signed a six-year, $48 million deal with the team in September 2004.

In 414 career games, he has averaged 10.6 points, 5.2 rebounds and 1.15 blocks.

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AP Sports Writer Anne Peterson in Portland, Ore. contributed to this report.