BEIJING, Aug. 21 (Xinhua) -- China's Ministry of Education on Tuesday ordered improved paper grading for school exams to ensure educational fairness.

The ministry gave the order after it announced the results of an investigation into grading errors reported at senior high school entrance examinations in Yan'an, northwest China's Shaanxi Province.

Machine errors were to blame for the incorrect grades 3,252 students received for their English exam, the ministry said.

It asked local educational authorities across the country to run a thorough check of every aspect of the high school entrance examination paper grading system -- including the procedure, management, technology, and supervision.

All problems need to be corrected in time, it said.