Three Foxconn workers have committed suicide at a factory in China in the past three weeks, a labour rights group said Saturday.

All three jumped to their deaths at a plant in the central city of Zhengzhou run by the Taiwanese electronics giant.

A 30-year-old married man killed himself on Tuesday following the similar deaths of a 23-year-old woman on April 27 and a 24-year-old man three days earlier, media reports said.

"The reasons for these building jumpings are unclear," the New York-based China Labor Watch rights group said in a statement.

Foxconn, which assembles products for Apple, Sony and Nokia, has come under the spotlight after suicides and labour unrest at its Chinese plants since 2010.

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

Although Foxconn denied the accusations, it raised wages by nearly 70 percent at its China plants in 2010.

It has also taken steps such as improving working conditions and enforcing age restrictions to address concerns raised by an independent audit of conditions mandated by Apple.

Foxconn is the world's largest maker of computer components and employs up to 1.1 million workers in China.