CHICAGO (CBS) — BP has announced as many as 80 layoffs at its massive refinery in Whiting, Indiana.

The company said the layoffs do not affect union employees at the largest refinery in the Midwest.

“BP expects a workforce reduction in the range of 50 to 80 salaried employees at the Whiting Refinery,” spokesman Brett Clanton said. “These changes do not include the union-represented hourly and salaried workforce at the refinery. BP will continue to comply with its collective bargaining commitments.”

The layoffs are the first mass job cuts at the refinery in 17 years. In 1999, BP laid off about 50 salaried workers and about 200 hourly employees.

About 1,800 BP employees and hundreds of contractors work at the 1,400-acre refinery. A statement from BP did not give a reason for the layoffs.

“We are always looking at our business to make sure that we have the right people in the right roles to operate efficiently, safely and reliably. BP is committed to treating employees with respect and dignity throughout this organizational change,” Clanton said.

Analysts have said falling crude oil prices and BP expenses from the disastrous Deepwater Horizon oil spill in 2010 were at least partly to blame for the layoffs at the Whiting plant.