About 500 students across the Chinese mainland will appear for the first Internet-based Test of English as a Foreign Language (TOEFL iBT) exam today.

The online exam, with a newly-added speaking section and first initiated in the United States last September, is to replace the written TOEFL test that was introduced to China 25 years ago.

The exam will initially be held at 15 centres in six cities: Beijing, Shanghai, Guangzhou, Tianjin, Hangzhou and Chengdu, offering 500 seats.

By the year-end, 10,000 people will have a chance to take the test at 19 centres in the six cities, according to the US-based Educational Testing Service (ETS).

"With the Internet-based delivery platform, both the number of test centres and the frequency of tests will increase significantly compared to five paper-based TOEFL tests offered annually," said Paul Ramsey, senior vice-president of ETS' international development department.

The 18 tests this year could increase to as many as 40 next year, he said.

ETS figures show that the Chinese now account for about 10 per cent of its global TOEFL examinees -- the most in the world -- and the number is growing.

Last year, about 90,000 Chinese students took the test, according to China's National Education Examinations Authority (NEEA), which helps ETS administer it in China.

Ramsey explained that the technology used in iBT permits test items to be delivered to ETS from sites worldwide, thus increasing the already-high security.

"It also ensures unbiased testing by recording responses in the speaking section electronically and sending them to a network of ETS human raters, who objectively score the responses for maximum reliability," he said.

So, how tough is the new test? Students believe it will be more challenging because of the new speaking section.

"Speaking is generally considered the Achilles' heel of Chinese students," said Li Ding, a TOEFL teacher with New Oriental School, China's biggest English-training institute.

He said many of his students rushed to take the last several written TOEFL exams to avoid the new one.