By Randy Fabi and Nicholas Owen

JAKARTA, May 18 (Reuters) - ManpowerGroup Inc, one of the world's biggest staffing firms, plans to expand into Indonesia as early as September, seeing an opportunity to tap companies that are struggling to find skilled labour in the Southeast Asian nation.

Strong growth in Indonesia's foreign direct investment has been a rare bright spot for President Joko Widodo, but could just as easily falter if firms can't find the engineers, accountants, and executives to run their businesses.

"Given the challenges employers are facing in Indonesia getting the right talent, this is a great opportunity for the ManpowerGroup to bring value to the Indonesia market," Sam Haggag, Manpower's director for Asia-Pacific, told Reuters.

U.S.-based Manpower, which already has offices in Vietnam, Philippines, Singapore, Malaysia and Thailand, decided to finally open a unit in Indonesia after more of its customers looked to invest in Southeast Asia's largest economy, Haggag said.

"President Widodo's government is very encouraging in regards to its commitment to growth and supporting FDI. It is driving our customers," he said, adding that more than half of the Fortune 500 companies are Manpower's clients.

Manpower saw "significant opportunities" in Indonesia in talent management and recruiting professionals for financial services, construction, engineering and information technology.

Haggag declined to say how much the company would initially invest in Indonesia.

The small pool of high-skilled labour is forcing Indonesian employers to promote professionals at a more rapid rate than their neighbours.

A survey by Monroe Consulting Group released on Monday found 31 percent of respondents in Indonesia having received a promotion within the last year, compared to 21 percent of respondents in other Southeast Asian countries.

"Companies are having to promote people on their potential to grow into the new position, rather than waiting until they have developed the experience and skills," the survey said.

Indonesia's poor education system, ranked last among 40 countries in a global Pearson index last year, has done little to improve a low-skilled workforce that lags behind its neighbours in competitiveness.

The government spends a fifth of its state budget on education, but its failing schools remain a major hindrance to Indonesia's economy.

(Editing by Muralikumar Anantharaman)