HELSINKI (AP) — About 30,000 Finnish metals and engineering industry workers began a strike Friday, expected to hit the country's vital export trade, with fears it could spread in two weeks' time.

The industrial action came after unions and management rejected National Conciliator Esa Lonka's mediation proposal on wages and working conditions, following days of negotiations.

The two-week strike will affect about 40 companies, including some of Finland's largest metals industry exporters. The union of professional workers has warned it would expand the strike to include 78 companies on Nov. 7, unless talks are resumed and agreement is reached.

The Federation of Finnish Technology Industries has estimated that a two-week strike would cost export companies $16 billion (euro11.5 billion) in lost earnings. The sector accounts for 60 percent of Finland's exports and 80 percent of all investments in the country's research and development.

Last week, central trade unions and main employers organizations agreed on the outlines of a centralized labor contract that would have hiked wages by 4.3 percent over two years for about 2 million workers. But local union chiefs in technological industries, including the metals and engineering sectors, rejected the deal against the recommendations of central trade union leaders.

Prime Minister Jyrki Katainen urged the parties to reopen talks, saying the strike could be disastrous for Finland's export-driven economy and scupper last week's outline for a centralized labor contract.

"I would like to be optimistic because so much is at stake," Katainen told reporters on Friday. "It's not just a question of a labor contract but of Finland's economy. I trust the negotiating parties realize how acute the situation is."