(Reuters) -Union members who assemble Boeing's fighter jets in the St. Louis area rejected the U.S. planemaker's latest contract offer on Sunday and will strike at midnight on Monday, the International Association of Machinists and Aerospace Workers union (IAM) said.

Boeing ( NYSE: BA) is facing the prospect of its first strike in nearly 30 years at its defense manufacturing facilities near St. Louis, after union members rejected a revised labor agreement.

Described by Boeing as its "last, best and final offer", the proposal includes wage increases beyond those offered in the deal previously rejected by union members.