The Union of Salaried Employees (TU), member of the Finnish Confederation of Salaried Employees (STTK), is preparing for industrial action in the metal and telecommunications sectors.
The metal sector strike would start on Monday and potentially expand after a fortnight.
Talks mediated by Juhani Salonius, the national conciliator, proved fruitless late on Tuesday.
The union is expected to announce on Wednesday how it plans to expand the strike.
The first phase of the industrial action in the metal sector would affect seven companies and 34 sites. Initially, up to 3,000 clerical workers would go on strike at shipbuilder Aker Yards, steelmakers Outokumpu and Rautaruukki, engineering group Wärtsilä, miner and smelter Boliden and Luvata, formerly known as Outokumpu Copper Products.
TU also issued a strike notice for the telecommunications sector, adding thousands of clerical workers would go on strike on 1 November.
The collective labour agreement in question applies to Elisa, Finnet, DNA and TeliaSonera.