TAIYUAN, Aug. 29 -- Taiwanese technology giant Foxconn's plant in north China's Shanxi Province has opened a massive recruitment drive as it needs an extra 20,000 workers to meet orders for next-generation smartphones.

The company's industrial park in Taiyuan, Shanxi's capital, already has a work force of 51,000 but needs to staff new production lines in which it has invested 3.2 billion yuan (520 million U.S. dollars), said a human resources executive who declined to be named.

He said the company needs to recruit as many laborers as possible as production is expected to keep expanding up to 2016.

Foxconn is the world's largest contract electronics maker and assembles products for top international brands including Apple, Sony and Nokia.

The company's smartphone production bases in Chinese mainland are mainly in Taiyuan, Zhengzhou in central Henan Province, and Shenzhen in southern Guangzhou Province.

The human resources executive said although Foxconn's plants are keen to use robots to replace human laborers, workers are irreplaceable in many fields such as quality testing and polishing.

Foxconn's plant in Shanxi exported 5.96 million mobile phones last year, earning 1.186 billion U.S. dollars, according to the provincial bureau of commerce.

Foxconn is a huge employer in China, with an estimated 1.2 million laborers on the mainland. However, it has been under fire in recent years after suicides and labor unrest at its plants were exposed.

In 2010, at least 13 Foxconn employees in China died in apparent suicides, which activists blamed on tough and high-pressure working conditions, prompting calls for better treatment of staff.

With Apple's plan to unveil the iPhone 6 on September 9, industry insiders believe Foxconn's plants in China's mainland need to recruit over 100,000 workers this year to keep up with coming orders.

Foxconn recruiters have been distributing leaflets to woo migrant workers at railway terminals in labor-rich inland Chinese provinces.