Volvo Trucks North America tripled a retirement benefit for managers and other nonunion employees 12 hours after unionized workers accepted cuts in starting pay and health coverage last week, Volvo officials confirmed Friday.

The company raised its 1998 matching contribution to nonunion employee 401(k) accounts from 25 percent to 75 percent. For every $1,000 saved by workers, the company will contribute $750 instead of the previous level of $250.

Marc Gustafson, president and CEO of Volvo Trucks, announced the added benefit in a Jan. 29 memorandum to his managers titled “rewarding success.”

“These decisions were made some time ago,” he wrote. “But we delayed their announcement in order to avoid complicating the recent labor negotiations, which were just concluded.”

Gustafson congratulated the nonunion workers on “the most successful year in our company’s history” and listed several benefits including a fifth week of vacation for employees with at least 20 years of service.