A massive stevedores' strike that on Thursday shut all of export-reliant Finland's ports will further weaken the country's already ailing economy, Prime Minister Matti Vanhanen said.

"This is a very serious conflict," Vanhanen told reporters, adding that the strike was costing the national economy "around 100 million euros" (136 million dollars) per day.

"Our economy is in recession and we should be trying to get a hold on the budding global economic growth. We really don't need these kinds of home-made drawbacks," he said

More than 3,000 stevedores walked off the job Thursday morning after last minute labour talks broke down without agreement before a 6:00 am (0400 GMT) deadline given by the transport workers' union, AKT.

The strike is a blow to the eurozone country, whose economy last year saw its biggest annual fall since 1918 as the global downturn dampened demand for key exports like paper and mobile phones.

Paper maker UPM-Kymmene was the first major industry player to report damages, saying it had closed a magazine paper mill in Rauma Thursday as the plant had no storage capacity for products, which would normally be delivered directly to the port for shipping.

Further shut-downs are expected in coming days, and the Confederation for Finnish Industries (EK) said the strike, which follows a one-day work stoppage by Finnish road transport workers, would dent the reputation and competitiveness of Finnish firms "permanently".

Around 80 percent of the Nordic country's foreign trade is transported by sea, according to EK, which says exports account for around 40 percent of Finland's gross domestic product (GDP).

No end-date has been announced for the stevedores strike.

Meanwhile, port cargo handlers are currently in labour talks, and some 500 workers could go on strike at 6:00 am Friday if the parties fail to reach an agreement in collective labour talks before then, AKT said.