Union says drivers should not be asked to give up established conditions as talks with Bus Vannin continue
Unite has claimed negotiations with Bus Vannin have yet to produce an authorised pay offer, nearly a year after talks began.
The union says the only idea put forward so far has been a provisional suggestion that would see drivers give up "long-standing" terms and conditions to fund their own pay increase - something it argues has not been asked of any other public service.
Unite maintains the dispute is centred on achieving fair pay and protecting established conditions, rather than seeking more than other government workers.
The union confirmed last week its members have now given a mandate for industrial action and that formal notice will be issued to the Department of Infrastructure.
Infrastructure Minister Michelle Haywood says her department remained committed to conversations through the recognised union channels, urging representatives to "come back to the table".
Bus Vannin has also said it remains committed to ongoing discussions.
Unite says it is prepared to negotiate "at any time", but insists progress requires a genuine offer rather than what it describes as a hypothetical proposal.
Manx Radio has approached the Department of Infrastructure for comment.
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