The National Basketball League has formally locked out its players after they failed to reach an agreement with the owners on a new collective bargaining agreement.

The lockout took effect early Friday morning when the previous labor deal expired. NBA owners announced the lockout hours earlier on Thursday, after a three-hour bargaining session in New York failed to yield any results.

The owners say the NBA lost $300 million last year, with just eight of its 30 franchises making a profit. They want to impose a strict salary cap on the players, curtail guaranteed contracts and cut the players' guaranteed share of the league's annual $4 billion revenue from 57 percent to 50 percent.

They rejected an offer by the players' union to reduce the players' guaranteed share to 54.3 percent, giving back $100 million a year for the next five years.

Friday's lockout is the first work stoppage in the NBA since the 1998-99 season, when the season was shortened to 50 games after a prolonged and acrimonious lockout. Observers say the current labor dispute could cost the NBA the entire 2011-12 season.

Under the lockout, players can not train at the team's facilities or work with the team's coaches. Franchises are also barred from making trades or negotiating contracts with rookies and free agents.

The NBA is the second major North American sports league this year to shut down operations due to a labor dispute. Players with the National Football League have been locked out since March, but the two sides are negotiating to reach a deal before the start of pre-season training camps set to begin later this month.