Aircraft wreckage and human remains from a recently crashed passenger jet were found by a rescue team according to the Civil Aviation Administration of China on Wednesday.

As of 7 pm on Wednesday, the rescue team has canvased an area of 46,000 square meters. What has been found has been passed to the investigation team, said Zheng Xi, head of the fire and rescue department of Guangxi Zhuang autonomous region, at a news conference on Wednesday night.

One of two "black box" flight recorders was found on Wednesday afternoon and was later identified as the Cockpit Voice Recorder, said Zhu Tao, head of aviation safety for CAAC. The China Eastern Airlines passenger jet carrying 132 people crashed into a mountain in Guangxi on Monday, and no survivors have yet been found.

He said the device has been sent to Beijing for further analysis.

"According to preliminary investigations on site, the exterior of the flight recorder was seriously damaged and the storage units also had a certain degree of damage. But the device remained comparatively intact," he added.

"It takes time to decode the flight recorder. If the storage units were damaged, it may take longer. After decoding the device, it will provide strong evidence as to the cause of the accident," Zhu said.

The jet had two flight recorders, both products of United States company Honeywell. One device records flight data, such as height, speed and direction, and the other records voices in the cockpit.

The team is making every effort to search for the other flight recorder, Zhu added.

According to Zheng, head of the fire and rescue team, natural impediments, including intermittent rain, steep hills and heavy forest growth around the area, has posed challenges to rescue work.

A team of firefighters has entered the core search area to drain a pond that was formed by last night's strong rainfall.