A Stormont minister is to meet counterparts in London to press for the retention of about 300 jobs at the Driver and Vehicle Agency (DVA) in Coleraine.
There are fears that the UK's Department for Transport (DfT) could axe or transfer the posts as part of moves to integrate and centralise services in Swansea.
Environment Minister Alex Attwood is to hold talks with the DfT next week to call for the Coleraine positions to be safeguarded. He warned the department that no decision should be taken without first consulting him.
Mr Attwood said he stood with the workers and unions in their campaign to protect the jobs.
"That has been a priority for me since the day and hour I became DoE (Department of the Environment) minister 20 months ago," he said.
"Over that time I have met the Department of Transport ministers twice, the NI Secretary of State, and had a number of conversations with London about the multiple reasons why the DVA jobs should stay."
The minister said he had backed industrial action taken by staff over the centralisation move.
"Last year the London Government announced this is what they would do and have now been doing in Britain - closing down vehicle licensing offices and moving the functions to Swansea," he added.
"To date, London have not said the same for NI in part because of DoE and union opposition. To keep my argument going and to protect the Coleraine jobs, I am again travelling to London next week to again explain to DfT why the jobs in Coleraine must stay. I previously sent a dossier to London outlining reason after reason why this was the right argument.
"DfT has said to me no decision would be made without consulting with me. I will hold London to that commitment and will continue the work of the last 20 months to protect jobs. London have made that pledge - it must not be reneged on."