A number of mainland students who recently took the International English Language Testing System (IELTS) exam have been left scratching their heads, as their results have been delayed or cancelled for unspecified reasons, the Beijing-based Mirror said.

Wang Xin, a college student in Beijing who took the test on August 1, received a text message saying that her scores would be on hold as the testing authority conducts a routine review.

But in September she received an email saying that her results would never be released due to a violation of regulations.

"It didn't specify which regulation in the email," Wang said.

Wang has joined a WeChat group with nearly 100 other test takers whose results are also being reviewed. Their test dates were July 25, September 1, 8, 13 or 29.

All test takers on the first three dates have been informed that their scores will not be released, crushing their plans of applying to foreign universities.

A well-known IELTS teacher said that the IELTS authority owes the students an explanation, and that he has already drafted a complaint on his Sina Weibo account. But Kuma, another teacher, believed the authority wouldn't reach a conclusion without evidence.

The IELTS's operator said the random review is being carried out to protect integrity and security, and that it has solid evidence that the cancelled scores do not reflect the test-takers' real English level. Further details will not be unveiled, it added.

Each student is charged 1,750 yuan ($275) to take the test each time.