Eighteen senior high school students who traveled across China to impersonate others in the important national college entrance exam have been rounded up and sent home by police.

The teenagers from east China's Shandong Province were exposed as illegal exam surrogates in Tianshui city, in the northwestern Gansu Province after one of them mistakenly signed his own name.

All 18 were second grade students of Yanggu County No.1 Middle School in Shandong.

On June 4, during the exam, a proctor noticed that a student crossing out his name on the test paper, and then writing a different one. After comparing the photos on his admission form and identity card, the proctor decided the student was an impostor.

The surrogate exam-taker allegedly confessed to the police that he and other 17 classmates were from Shandong. He said they were asked to sit the exam as surrogates for the real exam applicants.

The police detained two other people, Zhang Yuru and Wei Chengjia, who allegedly transported the students to Gansu.

Zhang told police she was a laid-off worker in Yanggu county and was paid to take care of two relatives, both exam surrogates.

Wei, a chemistry teacher of the Yanggu No.1 Middle School, said he was asked by others to bring students to Gansu.

The police were still investigating the case and had yet to identify the suspected the true organizers of the fraud, said Feng Jitang, a police officer of the Tianshui public security bureau.

The 18 surrogates were sent back to Shandong, said Feng. He said they had not violated the law. Zhang and Wei were detained for "disturbing the social order".

Feng told Xinhua that it was inconvenient for his bureau to issue more details.

Xinhua reporters twice went to Tianshui No.6 Middle School, where at least four of the real exam-takers were registered. However, Wang Tao, the vice head of the school said he was uncertain that his school had four students enrolled there.

The case and the seemingly slow investigation have fuelled rumors of who might be involved.

A string of cheating scandals, including test paper leaks and exam impostors, have plagued the national college entrance exam.

The Ministry of Education said on Tuesday that 2,645 people out of 10.38 million examinees were found cheating this year, down by about 800 over last year.

(Xinhua News Agency June 19, 2008)