Sunderland transport giant Arriva has downplayed claims a partial sell-off will threaten jobs in its rail and bus operations.
Articles in the German press over the weekend claimed parent company Deutsche Bahn (DB) was planning to sell off up to a a 45 per cent minority stake in Arriva and global freight logistics company DB Schenker.
The RMT railworkers' union says the move could have 'drastic consequences' for employees.
Doxford International-based Arriva operates bus services across Northumberland and County Durham and recently won the franchise to run trains for the area formerly operated by Northern Rail.
RMT General Secretary Mick Cash said: "This potential fire sale of a large chunk of DB’s UK rail assets has set the alarm bells ringing for all Arriva and DB Schenker staff who once again see their livelihoods traded from under them as nothing more than units on a balance sheet.
"The deal that is being racked up also exposes the flakey and unstable nature of rail franchising that allows a company to win a contract and then sell off lumps of it at what is nothing more than a corporate car-boot sale without any controls over who is getting a slice of the action.
"RMT is alerting our members to these threats and will respond in robust fashion to any threat to jobs and conditions."
But an Arriva spokesman defended the potential sell-off and said it would allow the firm to expand its operations: "Arriva has a strong track record of investment in the UK, investing £549million in the past five years and employing 28,000 people across the country," he said.
"Deutsche Bahn is considering a third-party minority holding in Arriva which is intended to continue the successful development of Arriva and enable further investments in future growth.”