HELSINKI, Feb 1 (Reuters) - Some 290,000 Finnish workers will begin two days of strike action on Thursday to protest against the right-wing government's planned labour market reforms and proposed cuts to the social welfare system.

Companies and labour unions said the strikes on Thursday and Friday were expected to halt much of Finland's air traffic, hit oil refinery output and close many shops, factories and kindergartens.

"The government's plan is cold-blooded. First, the right to strike will be severely restricted and then tough cuts are pushed through," Jarkko Eloranta, president of Finland's largest trade union association SAK, told Reuters.

In recent months, labour unions have protested against the government's plans to favour local work agreements over centralised bargains, limit political strikes and make it easier to terminate work contracts.

The unions have said they are up for a long fight if needed, threatening to follow up with more strike action if the government, which took office last year, does not back down.

The government has persisted, however, arguing that Finland needs to boost productivity and cut its fiscal deficit.

Top industry lobby EK and the government have also criticised the strikes, saying the changes are needed to bring Finland's economy on par with comparable countries such as neighbouring Sweden.

"Reforms are necessary and the unions have not offered any alternatives for correcting our alarming economic situation," EK chief executive Jyri Hakamies said in a statement.

The striking workers make up some 13% of the 2.29 million people employed in Finland, according to official statistics from 2023.

Finnish flag carrier Finnair on Monday said it would cancel some 550 flights due to the strike, while fuel producer Neste's Porvoo refinery will supply less petrol and diesel for approximately a week.

The umbrella union for university educated workers, Akava, urged the government not to abandon the Finnish tradition of negotiation.

"After this political action, the government is now forced to consider whether the trade unions will continue and how wide it can spread," Akava communications chief Jyrki Kemppainen said. (Reporting by Essi Lehto, editing by Terje Solsvik, Anne Kauranen and Kylie MacLellan)