COPENHAGEN, March 11 (Reuters) - Finnish stainless steel maker Outokumpu on Monday said it had cut its guidance for the first quarter of this year due to the labour union strike action against the Finnish government.

The company expects its first-quarter adjusted earnings before interest, tax, depreciation and amortisation (EBITDA) to be at a similar or lower level compared to the previous quarter it said in a statement.

The firm achieved 72 million euros in the fourth quarter last year.

"Assuming the strike will last for 14 days, the negative impact on adjusted EBITDA for Outokumpu is estimated to be approximately EUR 40 million," the company said.

About half of the negative financial impact is expected to be realized in the first quarter and the remaining in the second quarter, the company added. (Reporting by Louise Breusch Rasmussen, editing by Stine Jacobsen)