Vice-minister of Ecology and Environment Zhai Qing has led a supervision team to investigate an alleged large-scale deforestation case in Dunhuang in northwestern China's Gansu province.

The forest has protected the famous Silk Road city from sandstorms for decades.

The team has finished its investigation and is drafting its final report, ministry spokesman Liu Youbin said on Thursday.

Nearly 1,000 hectares of forest in Yangguan Forest Station, grown to fend off desertification, were illegally logged in the past decade and replaced by vineyards, Economic Information Daily reported last week.

The forest, on the edge of the Kumtag Desert, played a significant role in preventing sandstorms, conserving water and soil, and safeguarding agriculture.

Plans to create the forest began in 1963. After decades of continuous effort, it had 4 million trees by 2000, helping to prevent further expansion of China's sixth-largest desert.

Based on two satellite remote sensing images provided by authorities, the newspaper's report said the forest area under the supervision of the Yangguan Forest Station shrank sharply from 2000 to 2017.

Hours after the case was revealed last week, a special work team was established by Dunhuang's city government to look into it.

According to a report released by Gansu's provincial government on Tuesday, Yangguan has had 465 hectares of forest area all the time and there has been no massive deforestation at Yangguan Forest Station or cases of healthy forest being cut down and replaced with vineyards for profit.

However, Economic Information Daily issued a statement on Wednesday challenging the figures from the Gansu government.

Citing historical files on Yangguan, it said Yangguan claimed in many official documents to have had 866 hectares of forest area in 2016.

The Gansu provincial government has not responded to the latest allegation.

"The Ministry of Ecology and Environment attached great attention to the case and the investigation was conducted strictly, with the help of remote sensing satellites and drones," Liu said.

"We will also check the report by Gansu province and make the result public in a timely manner. If problems, such as dereliction of duty, are found, the ministry will urge the provincial government and related departments to shoulder their responsibilities."