Scottish Natural Heritage (SNH) staff are beginning legal action against a proposal to move them to Inverness.
The jobs will be transferred to Inverness
The Public and Commercial Services (PCS) union is to lodge a complaint with the employment tribunal in an attempt to prevent job losses caused by the relocation of the agency.
At present, about 270 SNH staff work from its premises in Edinburgh.
The Scottish Executive wants them to move to Inverness as part of its policy of dispersing public sector jobs.
Staff are concerned they could lose their jobs if they refuse to leave Edinburgh.
The PCS says SNH is in breach of employment law because it has not properly consulted staff about the reasons for the move or discussed ways of avoiding redundancies.
Although the action is being taken against their employers, union officials are making it clear that their real gripe is with the executive.