Samsung Electronics, the world's largest memory chip maker, plans to unveil on Monday a much-awaited semiconductor investment plan, a source said, joining a growing list of firms raising spending on global economic recovery.

Market speculation on the size of the investment has grown since the South Korean firm said two weeks ago that it would sharply raise capital spending this year, with some media reports penciling in a record 20 trillion won ($17.7 billion).

That would be more than double the original budget of at least 8.5 trillion that Samsung earmarked for this year.

Samsung declined to comment but said it would hold a ceremony on Monday to start building a new chip plant, which would mark the first construction of its kind in at least four years, after shunning expansion due to the industry's worst ever downturn.

As the chip sector recovers, spurred by stronger than expected demand from China and booming sales of memory heavy devices such as smartphones and tablet PCs, companies are gearing up to increase investment, threatening to derail the rebound.

Toshiba Corp, the world's No.2 maker of NAND-type flash memory chips after Samsung, said this week it would boost capital spending, mainly in its chip and infrastructure businesses.

Samsung competes with home rival Hynix Semiconductor, Japan's Elpida Memory, and Micron Technology of the United States in computer memory chips.

Shares of Samsung, Asia's most valuable technology firm, closed down 0.4 percent at 810,000 won.

(Reporting by Miyoung Kim; Editing by Jonathan Hopfner)

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