With frequent news about China's fake diplomas and exam cheating, American graduate schools are beginning to eye Chinese applicants with suspicion.

Although official figures do not exist for how many Chinese students apply to study in American universities each year, officials estimate that for every Chinese student accepted to the US, 10 have applied.

With such fierce competition, there is little surprise that some students are taking short cuts.

Although professors believe most Chinese applicants are honest and their records reflect true ability, they are catching more and more applicants with forged recommendation letters, doctored transcripts and ghost-written admission essays.

In a highly publicised incident in January last year, the Education Testing Service - the organisation that administers the US graduate school entrance exam, the Graduate Records Exam (GRE) - issued a letter warning all graduate school deans not to admit applicants solely on their high GRE scores after it accused a Chinese test preparation school of violating copyright by selling old GRE exam papers to students.

'We urge you, therefore, to treat all GRE and TOEFL [Test of English as a Foreign Language] test scores from China with caution,' the letter said.

That month, the US academic journal Chronicle of Higher Education profiled how easy it was for Chinese applicants to American universities to hire professional test-takers and writers for their applications.

This bad publicity is now having an impact.

'There is definite concern, and graduate schools are clearly paying attention,' said Dr Debra Stewart, president of the Council of Graduate Schools.

Although most graduate schools interviewed publicly claim they treat all applicants equally, off the record some have expressed misgivings about Chinese applicants.

One major concern shared by schools is students who, on paper, have excellent English-language skills but in reality cannot hold a conversation.

'Cheating happens with Chinese applicants - as well as applicants from every other country. I think it's more visible with the Chinese applicants because there are so many more of them,' said Dale Gough, director of International Services at the American Association of Collegiate Registrars and Admissions Officers.

To guard against admitting a dishonest applicant, some schools have adjusted their methods of evaluating all foreign applicants.

'If the letter of recommendation is too good, we assume it is fake,' said Professor John Zhang, of New York University's chemistry department.

Virginia Technology University now requires all foreign students to take an English-language test as soon as they arrive. The University of Pennsylvania's Wharton School of Business sends its admissions officers to Beijing and Shanghai to interview applicants. The University of Colorado in Boulder requires applicants to send letters of recommendation and transcripts in both Chinese and English.

Many of the larger universities, particularly those with a Chinese faculty member or those with exchange programmes with Chinese universities, now contact the applicants' former professors by phone or e-mail.

However, these methods are a luxury only a few schools can afford.

'Too many US institutions really don't have staff sufficiently trained or experienced to catch alterations,' Mr Gough said.

In an attempt to reduce academic fraud, China's Supreme Court recently ruled that people caught forging graduation diplomas could face criminal charges and up to three years in jail. The Education Ministry has launched a database that provides serial numbers to check diplomas online.

However, these measures only tackle domestic fraud.

US officials hope more can be done. Dr Stewart said the US side was trying to be fair but needed more help from Chinese officials.