At least 40 people have been killed and an unknown number of others are trapped after a scaffolding platform collapsed on a Chinese construction site.

An official at the Fengcheng Work Safety Administration said a platform at a power plant's cooling tower that was under construction collapsed on Thursday morning, in Fengcheng in the country's south-eastern Jiangxi Province.

Five injured workers have been taken to hospital.

The incident took place at around 7.30am local time and rescue workers are on the scene.

China has suffered a series of major industrial accidents over recent months blamed on corruption, disregard for safety and pressure to boost production amid a slowing economy.

The country has vowed to improve safety on industrial sites, with President Xi Jinping saying authorities would learn the lessons paid for with blood after chemical blasts in the port city of Tianjin killed more than 170 people in August 2015.