The replacement of humans by machines in the workplace took another step on Wednesday, as Japanese researchers unveiled a model they hope could lead to humanoid menial workers.

Its makers, Kawada Industries and the National Institute of Advanced Industrial Science and Technology (AIST), hope the robot will be a step towards creating a model that can help ease greying Japan's looming labour shortage.

"We designed a working robot in the image of a lean but well-muscled track-and-field athlete," Noriyuki Kanehira, robotic systems manager at Kawada, told a news conference to unveil the blue-and-white "HRP-4."

Designed to help researchers develop models that could replace humans in repetitive manual labour, the latest "athlete" model in a near 10-year-old series updates the feminine, catwalk-strutting, karaoke-singing HRP-4C.

But the tone this time is altogether more serious, according to a joint statement from its developers.

"It is Japan's urgent task for the early 21st Century to develop robots that could carry out simple, repetitive works ... in a bid to complement the workforce in a country that is rapidly ageing with fewer and fewer children".

Standing at 151 centimetres (59 inches) tall, the robot in a demonstration Wednesday stood on one foot, twisted its waist, struck poses, walked in accordance to given voice commands and moved its head to track objects.

The HRP-4 boasts joints that move more freely than its predecessors and can run a range of separately-developed software applications, its makers said.

Kawada and AIST will start selling the robot to universities and research institutes in Japan and abroad from January 2011.

The price tag for what is described as a "low cost" model is 26 million yen (306,000 dollars) each. Its creators hope to sell three-to-five units a year.