Boeing said on Tuesday that it had withdrawn its pay offer to around 33,000 U.S. factory workers and no further negotiations were planned with their union representatives as a financially damaging strike nears its fourth week.

Boeing and the union that represents 33,000 striking employees at the company say talks between the two have broken down and no new talks are scheduled.

The breakdown extends a machinist strike at Boeing that has halted production of most of the company's aircraft.