Boeing says it has withdrawn its pay rise offer to striking workers after negotiations with union representatives reached a stalemate.

The aviation giant accused the union of not giving its proposals serious consideration.

The International Association of Machinists and Aerospace Workers union (IAM) said Boeing was “hell-bent on standing on the non-negotiated offer” which it says was rejected by its members.

Last month, Boeing announced what it called its “best and final” offer to workers, which proposed a 30% rise over four years – lower than the 40% being demanded by the union.

“The union made non-negotiable demands far in excess of what can be accepted if we are to remain competitive as a business,” Boeing Commercial Airplanes President Stephanie Pope said in a letter sent to employees.

“Given that position, further negotiations do not make sense at this point and our offer has been withdrawn.”

But union representatives said Boeing was not willing to negotiate the terms of plane maker’s latest offer.

“They refused to propose any wage increases, vacation/sick leave accrual, progression, ratification bonus, or the 401k Match/SCRC Contribution. They also would not reinstate the defined benefit pension,” the IAM said in a statement.

More than 30,000 Boeing workers in the northwest of the US went on strike last month over pay and retirement packages.