According to the State Administration of Foreign Experts Affairs, although only 582 institutions in Shandong province are allowed to grant work visas to foreign teachers, thousands of institutions employ expats.

At an institution in Qingdao, Shandong province, a staff member said applicants' resumes were always checked, but refused to say whether the expats listed in the advertising brochure had work visas or TEFL certificates.

"They are all white people. No need to worry about their teaching level. Believe me they are all experts and they can speak fluent English," said the woman, who declined to be named.

Zhang, of Yanshan University, said it can be difficult to hire competent teachers, but that's no excuse for employing people illegally.

"In addition to setting higher standards for applicants, the regulators have to do more to ensure the policy is enforced. The policies issued by the State Administration of Foreign Experts Affairs lack legal constraints," he said.

He said a special agency is needed to verify and evaluate the qualifications, competence and ethics of expat teachers. It should also help foreign-language teachers improve their professional skills by providing useful resources and courses, and by helping them to secure positions in a market that is bound to become increasingly competitive.

what they say

My 12-year-old son is taking an online oral English class with a teacher from the Philippines. The teacher chats with my son on Skype. I don't know whether the teacher has obtained a teaching certificate or not. Actually, I know nothing about the employment procedures, I just think the class is quite cheap. It only costs 30 yuan ($4.50) an hour. I'm not expecting that my kid will learn a lot from a foreign-language teacher. I just want my son to practice English with a native speaker.

Cai Wenqing, engineer in Beijing

My daughter is 18 and she is taking a TOEFL class with a teacher from the US. He is very capable, I think, and gives my daughter a lot of good advice about the college application process, which is quite confusing and overwhelming for me. I don't think he represents the general level of teaching competency of expat teachers in Beijing. All I can say is that I am quite satisfied with my daughter's teacher.

Li Jialai, high school math teacher in Beijing

I don't think foreign teachers can help my daughter a lot. I think foreign-language teachers are able to help my daughter to improve her pronunciation, although I am not sure to what extent that the teachers could help her improve. I don't speak English, and I don't think my daughter needs to take oral English classes now. She is in the ninth grade, and she is preparing for the high school entrance exam. Chinese teachers will better help her prepare for the exam, I think.

Shi Na, doctor in Tianjin