Meanwhile, results for the Ordinary National Educational Test (ONet) will be announced on April 7-8, instead of on April 10 as previously scheduled, said Prof Uthumphorn Jamornman, director of the National Institute of Education Testing Service (NIETS).

The results will be sent to schools first so that they are available through more channels, she said.

A total of 153,550 students sat the 11-subject A-Net exams. About 100 students yesterday registered with the Office of Higher Education Commission (OHEC) for their scores to be checked. Most said their scores were much lower than expected and some said results posted on www.cuas.or.th kept giving different scores each time they checked.

"The first time I checked, I got 45 in Social Studies 2 and 74 in English language 2, and

that become 55 and 40 marks respectively the second time I checked," said one student, while another student said his Maths 2 score was unusually low because the test was very difficult.

Sililtip Pakthawat from Suan Kularb Wittayalai School in Nonthaburi said that she wanted to check her English 2 and Science 2 scores. In the latter subject she expected at least 40 marks but only got 34 - about what someone answering the exam solely on guesswork would get, she said.

After students register to check their results, which OHEC allows them to do for 60 days after they are announced, the office appoints times for them to scrutinise their exam papers from March 30 onwards. Only 100 students will be allowed to see their papers each day so as to be able to thoroughly check their scores and be satisfied, according to OHEC secretary-general Krisanapong Keeratikorn.

However, Krisanapong said he was confident the office's exam-checking was not at fault because some students who got lower-than-expected scores found for themselves that they had chosen the wrong answers. As for the results that kept changing, Krisanapong said he would have officials check for errors.

He also dismissed students' complaints that the Maths 2 paper was too difficult, saying that all tests were according to the curriculum, Maths 2 results were similar to last year's, and no one scored a zero, he said.

Although the A-Net results were announced early, the universities will keep their admission period from April 11 to 23 because they have to also wait for O-Net results and each student's GPA and GPAX first, Krisanapong said.

Sompong Chitradab, a lecturer at Chulalongkorn University's Faculty of Education, suggested that the students' complaints about A-Net scores might stem from their anticipation of problems about O-Net and A-Net results and university admission, as happened last year. He urged OHEC to restore people's confidence and said registering students for score-checking was a positive solution.

He said the O-Net and A-Net exams were credibly organised this year and all loopholes were filled, so the incidence of errors should be low as 3 to 5 per cent.