Five former managers from a major crate and pallet manufacturer that employed illegal immigrants have pleaded guilty.

The plea comes ten months after federal agents staged sweeping raids at IFCO Systems sites in 26 states.

In April, more than 1,100 people were arrested on administrative immigration charges at more than 40 IFCO sites. The government has said that more than half the company's roughly 5,800 employees during 2005 had invalid or mismatched Social Security numbers.

Prosecutors say a company executive and a former general manager of the company's Albany, New York, plant could face up to two years in prison and a $250,000 fine.

Three local plant officials could face up to six months in jail and $3,000 fines for each illegal alien employed.