(Reuters) - The SAK trade union association said on April 4 that Finnish labour unions would suspend a four-week strike which began on March 11.

The strikes have disrupted Finland's ports and rail system, impacting imports and exports.

They were launched to protest against government plans to reform the labour market and reduce social welfare, changes that the government says are necessary.

Here is how some companies have been affected:

BOLIDEN

The Swedish metals maker on April 23 said that the now-suspended strikes had hurt its earnings by 400 million Swedish crowns ($36.51 million) in the first quarter, and estimates a one-off positive effect of 200 million crowns in the second quarter as inventory will be released.

FINNAIR

Strikes forced Finland's national carrier to cancel about 550 flights and reorganise refuelling operations as fuel deliveries were suspended for two weeks, hitting its revenue and earnings, Finnair said.

Interim CEO Jaakko Schildt told Reuters on April 23 that during the two-week fuel strike Finnair saw seven-digit damages in euros.

"During the two-day strike, when Finnair hardly flew at all, we are talking about millions of euros in damages per day," he added.

KEMIRA

The chemicals company said it had seen limited impact from the strikes on its first quarter results, but that they had forced some of Kemira's Finnish pulp and paper customers to curtail production in March and early April.

Kemira stopped production at several of its manufacturing lines, with some employees' work and salary payments suspended.

KEMPOWER

The maker of charging solutions for electric vehicles cut its first-quarter guidance on March 22, citing delivery delays. It saw first-quarter revenue significantly below the year-ago number, and operative earnings to be "significantly negative", it said in a statement.

METSA BOARD

The forestry firm said it was forced to stop production at all of its Finnish mills due to the strike, citing halted raw material transports to mills and port closures preventing customer deliveries.

It estimates that the strikes caused profit losses of roughly 25 million euros ($26.81 million), around half of which were allocated to the first quarter.

NESTE

The oil and biofuels group on April 25 said its first quarter EBITDA had been impacted negatively by about 10 to 15 million euros. It previously flagged it would stop production at its Porvoo oil refinery as the strike cut off raw material transportation and led to filling up of storage facilities.

NOKIAN TYRES

Strikes led the tyre maker to temporarily lay off 350 employees in March.

Its CEO Jukka Moisio on April 29 said the company lost about three weeks of production in passenger car tyres and one week in heavy tyres. Combined with the disruptions in the Red Sea, the strikes cost the company about 20 million euros in lost EBITDA.

NURMINEN LOGISTICS

The logistics firm said strikes had reduced its net sales and impaired its results, but that the full impact on revenue and operating profit would not be seen until the second quarter of the year. It did not quantify losses.

OUTOKUMPU

Stainless steelmaker Outokumpu on March 21 lowered its first-quarter core profit guidance for the second time.

It estimates the combined negative impact of the three-week long strike on adjusted EBITDA at about 65 million euros, a spokesperson said.

SSAB

The Swedish steelmaker earlier estimated the strike would shave off about 350 million crowns from SSAB Europe's first-quarter operating result.

CEO Martin Lindqvist on April 24 told Reuters that the company would book another 125 million in costs related to the strikes in the second quarter.

STORA ENSO

After halting production at some of its mills at the end of March, suspending wages for affected employees and ramping up production in April, Stora Enso on April 25 said the strike had hit its quarterly results by 25 million euros.

UPM

The forestry company on April 25 said the impact of the strike on its business had been modest, despite having halted production at various paper and pulp mills during the strike and suspending pay for employees involved.

VR GROUP

The state-owned railway, which normally runs 250 freight trains per day, said the strike would keep freight traffic at a standstill until April 7. Passenger transport would not be affected.

($1 = 10.9551 Swedish crowns)

($1 = 0.9326 euros)

(Reporting by Elsa Ohlen and Elviira Luoma; editing by Jason Neely and Christina Fincher)