Supplies of newsprint in Finland might soon run short, according to a commercial media lobby group's Managing Director Jukka Holmberg.
"After Russia's attack on Ukraine media firms have decided to stop using Russian paper," said Holmberg. "With UPM's strike continuing we could soon have big problems."
Around a fifth of Finnish newspapers were printed on Russian paper before the UPM strike started this year.
The supply issues were so acute that Helsingin Sanomat announced in March that it would reduce the size of weekend editions due to the paper shortage.
The price of newsprint has increased from 390 euros a ton last year to more than 670 euros a ton now. The supply issues seem to have caught printers by surprise.
"There has not previously been a shortage of paper and it has been obtainable quite quickly," said OP analyst Jari Parkkinen. "Everyone has kept stocks low, so as not to unnecessarily tie up capital."
Meanwhile a settlement proposal has been tabled by labour conciliator Leo Suomaa in a dispute between the paperworkers' union and UPM's pulp division, which is part of a broader UPM dispute.
He has given both sides three weeks to consider the offer. UPM Pulp manager Juha Kääriäinen said that he was 'hopeful' of a deal, while the union has said it would aim to resolve disputes in all departments at UPM before the deadline passes.
The union had recently extended the strike mandate to run until 16 April.
The strike at UPM plants started in early January, when UPM refused to continue the old collective agreement until a new agreement was reached, as is normal practice in Finland.
Finland has traditionally used collective agreements covering an entire sector, giving legally enforceable rights and minimum wages to workers even if their own firm is not a party to the agreement.
Industrial employers decided to agree company-by-company deals instead this time, but UPM went further, asking for deals specific to each individual plant.
The firm also declined to begin talks about a new deal for admin staff, who were simply notified of their new terms and conditions, according to their union.
The strike was recently cited by a UK Minister as a cause for concern in food supply, as UPM is responsible for a large proportion of the self-adhesive labels used in global food manufacturing.