Suntory spokesman Martin Cole, contacted in Sydney yesterday, confirmed all 800 staff in the combined New Zealand and Australian operations had been told of the sale process.
He expected it could take six to nine months.
He was aware of the recent Cadbury closure in Dunedin, highlighting Suntory had invested in the plant last year to boost production.
''I want to stress this is not about [factory] performance, but Suntory focusing on its beverages . . . food has been a very small part of its business.''
When asked what would happen should the businesses not sell, he said the operations in Sydney and Dunedin ''would be retained'' by Suntory.
He declined to say what the asking price was, but confirmed the business had been profitable in recent years.
The businesses were ''attractive, good performers''.
Otago Chamber of Commerce chief executive Dougal McGowan said confirmation of the sale process came as a ''surprise''.
''It is a sign of changes happening globally in the food production sector,'' he said of corporates rationalising or restructuring subsidiaries in other countries.
Both Cadbury and Greggs had spent tens of millions of dollars recently in redevelopments.
Mr McGowan said, as another ''major employer'' in Dunedin's's food sector, he would have wanted more detail from Suntory on what issues it was facing, and know more about any prospective buyer.
''We've just got to hope Suntory are genuine in wanting to sell Greggs and not [ultimately] just close it down,'' Mr McGowan said.
The potential sale also came as a surprise to Otago Southland Employers Association chief executive Virginia Nicholls, who hoped a new owner would consider further expansion.
''[However] it's concerning to hear that there is a sale process under way of another Dunedin iconic manufacturer, which have been manufacturing coffee in Dunedin since 1869.''
Ms Nicholls said Greggs' Dunedin factory was well situated, and purpose-built, with a high-calibre team. It was ideally located at an international port for importing coffee beans.
''We may find that a new owner may consider expanding the factory,'' Ms Nicholls said.