HELSINKI, March 6 (Reuters) - A planned two-week strike action by Finnish labour unions could bring Neste's Porvoo oil refinery to a standstill next week, the company told Reuters on Wednesday.

Finnish unions have for months protested against the right-wing government's plan to favour local work agreements over centralised bargains, limit political strikes, cut social welfare and make it easier to terminate work contracts.

Unions representing industrial, transportation and electrical workers on Wednesday said they would go on strike from March 11-25.

"The measures will target export and import operations at ports and the railway system," Finland's largest trade union association SAK said in a statement, adding that major industrial plants and distribution terminals would also be affected.

Neste said the conflict would force it to stop production at the Porvoo refinery a few days after the strike starts.

"This is due to raw material transportation being cut off and product storages filling up," Neste said in an emailed statement.

The refinery's output was also hit in January following two days of strike action.

The government and business lobbies say Finland needs to boost productivity and cut its fiscal deficit to maintain its welfare system.

The Porvoo refinery processes around 10 million tonnes of crude oil annually. (Reporting by Essi Lehto, editing by Terje Solsvik and Milla Nissi)