Experts from public security departments have begun examining the DNA of human remains at the site where a China Eastern Airlines jet crashed on Monday in the Guangxi Zhuang autonomous region, a local police chief said on Friday.

More than 236 experts were engaged in the painstaking work of collecting biometric information at the site, examining DNA and identifying victims, said Lao Gaojin, head of the wuzhou public security bureau, at a news conference in Wuzhou on Friday afternoon.

"As of 3 pm Friday, we have collected 18 fingerprint samples from the human remains and 101 items of passengers' belongings," Lao said. He added that the search area was further expanded on Friday to 200,000 square meters.

China Eastern Flight MU5735 left Kunming, the capital of Yunnan province, at 1:11 pm Monday with 132 people onboard and was scheduled to arrive in Guangzhou, Guangdong province, at 3:05 pm. Air traffic controllers lost track of the plane over Wuzhou at 2:21 pm.

Zhu Tao, head of the Civil Aviation Administration of China's aviation safety office, said that although no survivors have been found yet, the search and rescue teams have not given up hope.

Huang Shangwu, a Guangxi Fire and Rescue Brigade officer at the crash site, told China Daily that muddy conditions caused by previous heavy rainfall posed great challenges to the search and rescue work.

"Also, because the site is in the mountains covered by forest, some of the plants are taller than the members of the rescue team, and there are some very steep slopes. But despite the difficulties, we are determined to comb the area thoroughly and to continue to look for survivors," Huang said on Thursday.