BERLIN — Nokia said Thursday it would slash 10,000 jobs, or 19 percent of its workforce, by the end of 2013 as part of an emergency overhaul that includes closing research centers and a factory in Germany, Canada, and Finland, and the departures of three senior executives.

The company also warned investors that its loss was likely to be greater in the second quarter, which ends June 30, than it was in the first, and that the negative effects of its transition to a Windows-based smartphone business would continue into the third quarter.

Nokia, based in Espoo, Finland, posted a loss of $1.2 billion in the first quarter as sales plummeted 29 percent. Once the undisputed global leader in the cellphone business, Nokia has been outcompeted by Apple, as well as by Samsung and other makers of handsets running Google’s Android operating system.

In February 2011, Nokia and Microsoft announced an alliance to produce a line of smartphones called Lumia running the Windows operating system.

Since then, the Finnish company has seen its sales fall and profits evaporate as consumers and operators have avoided, or demanded discounts on, smartphones running Nokia’s in-house Symbian operating system, which the company is phasing out. Although Lumia devices have won critical praise, sales have not been strong enough to offset declines in its main business.

‘‘These planned reductions are a difficult consequence of the intended actions we believe we must take to ensure Nokia’s long-term competitive strength,’’ said Stephen Elop, the Nokia chief executive and a former Microsoft executive. ‘‘We do not make plans that may impact our employees lightly, and as a company we will work tirelessly to ensure that those at risk are offered the support, options and advice necessary to find new opportunities.’’

The company said the job reductions, and the shutdowns of research and development centers in Ulm, Germany, and Burnaby, Canada, and a handset factory in Salo, Finland, would save $2 billion euros by the end of next year. As part of its streamlining, Nokia announced the sale of its luxury handset business, Vertu, to EQT VI, a European private equity firm, for an undisclosed price.

The company also said it had purchased Scalado, a maker of smartphone imaging technology that is based in Lund, Sweden. It did not say what it paid for Scalado. Further, Nokia said it would ‘‘closely assess the future of certain noncore assets.’’

In a conference call with journalists, Elop suggested that Nokia Siemens Networks, the company’s 50-50 network equipment venture with Germany’s Siemens, which lost a combined $1.2 billion in 2010 and 2011, could be one of the businesses in the focus of its future review.

Elop declined to describe Nokia Siemens as a noncore asset but said the network gearmaker’s restructuring, now in its second year, was designed to make it more attractive for potential investors.

‘‘What we have said is that Nokia Siemens is going through its own restructuring, and we are pleased with the efforts so far,’’ Elop said. All the restructuring is being done to make it ‘‘a more independent entity in future,’’ he added. ‘‘As that proceeds, we will make a determination to see what the future holds.’’

Nokia said 3,700 of the planned 10,000 jobs to be cut would take place in Finland. The handset factory in Salo to be closed is Nokia’s largest in the country, and about 850 employees will be affected there by the reductions. Nokia plans to keep a research center in Salo open.

The Nokia executive responsible for Nokia’s bulk handset business, Mary T. McDowell is one of three senior level executives who will be leaving the company at the end of this month, Nokia said. Jerri DeVard, the chief marketing officer, and Niklas Savander, the executive vice president of markets, will also leave.

McDowell, an American and a former Hewlett-Packard executive, had been with Nokia since 2004. DeVard, an American who had worked in marketing at Verizon, Citigroup, and Revlon, had joined Nokia in January 2011. Savander, a Finn, had served in a variety of senior roles since joining Nokia in 1997.

Nokia promoted three Finnish citizens and two Americans as replacements. Juha Putkiranta was named executive vice president of operations; Timo Toikkanen was appointed executive vice president of cellphones; Chris Weber, an American, was named executive vice president of sales and marketing; Tuula Rytila was appointed as senior vice president of marketing and chief marketing officer; and Susan Sheehan, an American and former Microsoft executive, was named senior vice president of communications.