URUMQI, April 26 (Xinhua) -- Four Japanese citizens have been fined 20,000 yuan (about 2,590 U.S. dollars) for illegal mapping and surveying activities in northwest Xinjiang Uygur Autonomous Region, the regional bureau of surveying and mapping said on Thursday.

The four Japanese scholars, including Hidehiro Soma and three others, were asked by Japan's Research Institute for Humanity and Nature to carry out research into the ecological and environmental changes in the Ebinur lake, a salt lake in Xinjiang.

On March 5, the four men used GPS equipment to survey and map the area. Li Quanzhan, director of the bureau, said they had not obtained approval to carry out such mapping activities and their act had violated relevant Chinese laws.

"It was disrespectful to Chinese laws and their actions will not help research cooperation between the two countries," he said, adding that the bureau had confiscated the surveying equipment and results.

The four Japanese people later apologized and promised to abide by Chinese laws in future research activities in the country.

Last April, two Japanese scholars were fined 80,000 yuan (10,250 U.S. dollars) and deported for mapping the coordinates of an airport and water facilities in Hotan of Xinjiang.

Statistics from the bureau showed there were 759 cases of illegal surveying and mapping in 2006, many of which involved foreign organizations and individuals.

According to a new regulation which came to effect on March 1 this year, foreign organizations and individuals who intend to engage in surveying and mapping must obtain approval from the central government and be supervised by local governments.