"We had two pillars we stood on: one was the IT industry, the other one was the paper industry," Stubb told Swedish financial newspaper Dagens Industri.
"Nalle Wahlroos, president of (Swedish bank) Nordea, described it quite well when he said the iPhone knocked out Nokia and the iPad knocked out the forestry," accelerating the fall of paper demand.
Stubb became prime minister at the end of June with an economy struggling to recover from two years of recession. Only timid growth is expected in 2014.
"Our forestry is slowly but surely shifting from paper to bioenergy. Our IT industry is moving towards gaming, it's not just about hardware like the Nokia mobiles."
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The main symbol for Finland's economic difficulties was the fall of Nokia, the one-time world leader in mobile devices, which in April sold its loss-making handset business to US software giant Microsoft.
Stubb, a champion of liberalism and European integration, warned that he could not promise an immediate shift in the economic landscape.
"We shouldn't create the illusion that the state can create growth," Stubb said.