A number of firms are involved in talks about taking over the site, including telecoms and energy service provider Empower Oy.
Jouko Ahonen, chairman of the Finnish Paper Workers Union, said patriotic investors were prepared to buy the mill.
"The mill could have been sold and it would not have even competed with products UPM is manufacturing," Ahonen told Finnish newspaper Keskisuomalainen. "The jobs could have been saved."
Voikkaa is set to close in the third quarter of this year as UPM seeks to cut costs and reduce capacity across its operations.
Finns fail to attract paper interest
UPM is in discussions over the sale of its Voikkaa paper mill site in Finland, but has yet to receive an offer from a company that will continue paper production.
