April 12 (Reuters) - The United Auto Workers (UAW) said

on Friday it is "extremely disappointed" with truck maker Volvo

Group's decision to set up a new truck plant in

Mexico, which the company said would help supplement its U.S.

production.

The union, in a letter published on Thursday, said it is

looking into the contractual obligations for truck build rates

at the Lehigh Valley Operations (LVO) plant and the potential

legal ramifications from Volvo's Mexico decision.

Volvo announced the new plant on Thursday and added that it

would be investing an additional $80 million for future

production at the LVO plant, having invested $73 million over

the last five years.

"This is a slap in the face for all of us," said UAW Local

677 shop chair Tim Hertzog, adding that the company informed the

union about the plans 15 minutes before the announcement.

Volvo was not immediately available for a comment on Friday.