NEW YORK (CNNMoney.com) - General Motors, Delphi Corp. and the United Auto Workers union could announce an agreement on voluntary early-retirement packages for union workers as early as Friday evening, according to a report in the online edition of the Wall Street Journal.

The final details of a deal are still being worked out and the negotiating session could still break up today without an agreement, the newspaper said, citing three people familiar with the matter.

But the three sides have been making preparations in case they have a deal to announce before the weekend, the report said.

GM spokeswoman Katie McBride said talks are ongoing and that the automaker hopes to wrap up discussions as soon as possible. "When something is reached, we'll be able to communicate further," she told CNNMoney.com.

Delphi spokesman Lindsey Williams also confirmed that negotiations are ongoing but declined to give a timeline for reaching a deal.

The UAW could not be immediately reached for comment.

The size of the buyout packages and how many union workers GM (Research) and Delphi hoped would accept early retirement was not yet known, according to the Journal.

The closely watched talks are viewed as crucial for GM's efforts to avoid bankruptcy and to shave costs. The company is on record as saying it may be responsible for up to $12 billion in payments to its former employees due to agreements signed between Delphi, the UAW and GM when the former GM parts unit was spun off as a separate company in 1999.

Delphi, which filed for bankruptcy in October, is still the largest parts supplier to GM, and a long strike could cripple the carmaker and force it to file bankruptcy. But most experts believe that there is little chance of such a prolonged strike.

The agreements GM reaches with Delphi are also expected to set the tone for its labor negotiations next year.

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