Delta Air Lines Inc., the world's largest carrier, will give most workers raises of 3 percent, while increases for unionized employees at newly acquired Northwest Airlines Corp., will be half that amount.

Noncontract employees will get a 3 percent to 4 percent boost starting Jan. 1, Delta Chief Executive Officer Richard Anderson said Tuesday in a memo. Unionized workers, including Northwest flight attendants and mechanics, will get 1 percent to 1.5 percent as stipulated in their existing contracts, he wrote.

While Delta and Northwest pilots have already agreed on a new, higher-paying joint contract, the disparity in raises among other workers underscores tensions between groups that are unionized at Northwest but not at Delta.

"It's unfortunate that throughout these sensitive times management is trying to pit one group against another," said Corey Caldwell, a spokeswoman for the Association of Flight Attendants in Washington, which represents the Northwest chapter. Delta's flight attendants aren't unionized.

Delta's raises are part of an effort to bring employee pay back up to "industry standard" by 2010, Anderson said in the memo. The airline slashed wages before and during its own bankruptcy, which ended in 2007, to help lower costs. Delta most recently gave its workers 3 percent increases in July.

The carrier has already agreed to give all pilots a 5 percent boost in 2009, followed by 4 percent increases in each of the next three years in exchange for greater flexibility in scheduling while Delta and Northwest integrate operations.