A group of workers at the Nissan car plant on Wearside have voted for strike action.
The dispute surrounds a decision by the car giant to relocate of the company's purchasing department.
Members of Amicus voted by 17 to 5 in favour of industrial action in protest at being told to move from the factory in Sunderland to a site in Cranfield, Bedfordshire.
The union complained that the workers were not consulted over the transfer and had been treated like "robots".
But Nissan said it had offered an extensive relocation package for those workers who want to move.
Amicus has said its officials will hold talks with the workers to decide their next move.
It is the first threat of strike action since the Sunderland factory opened in 1986.
In a statement Nissan said out of 70 staff in the department, only 17 have voted yes, five voted no and the remaining 18 Amicus members did not return their papers.
It read: "We shall be contacting the employees' elected representatives and the Union as soon as possible.
"Nissan is keen to retain its Purchasing staff and has already offered attractive relocation terms including six years mortgage interest support for an increase in mortgage cost of up to £75,000, and up to £7,500 in relocation allowances.
"We are also trying very hard to find alternative employment at Sunderland for those who do not wish to move.
"We have offered a severance package, which includes a payment of about £17,500 to a typical Buyer in Purchasing, plus outplacement services and other support.
"We have had a good record of employee relations in the past and this has helped us secure investment in new models."