'My travel has been often arranged by my students who, as senior officials, can use public money to pay all of my expenses,' said Professor Wan, a law lecturer at one of the mainland's leading universities who asked that his full name not be used.

Higher degrees, particular those granted by top universities, are highly sought after by officials seeking promotion because the government has made education a key criterion for advancement.

Since then academic qualifications have become a saleable commodity, in legal and illegal ways, prompting the Communist Party leadership and its powerful Organisation Department and Central Discipline Inspection Commission to crack down on malpractice.

In one campaign that investigated 670,000 mid- and high-level cadres a few years ago, the party's Central Committee found more than 15,000 top civil servants had been using fake qualifications.

Some of those caught in the sweep had exaggerated their qualifications, while others were found to have degree certificates from institutions that were not entitled to issue them. A few bought or made fake certificates.

Mainland media have carried numerous exposes of party officials who used counterfeit diplomas to advance. One was Hu Changqing , a former deputy governor of Jiangxi , who was executed for taking bribes.

He had claimed to hold two degrees - one in law - from Peking University but had actually bought phony diplomas near the campus.

To improve the intellectual calibre of its civil servants, Beijing has insisted over the past decade that each leading cadre have a degree. A further degree is seen as being even better.

There has been a corresponding great leap forward in the educational achievements of officials. At the party's 17th national congress, many more new leaders in the 204-member Central Committee, the 24-member Politburo and the nine-man Politburo Standing Committee were master's or PhD holders.

Xi Jinping and Li Keqiang , the two most prominent new members of the Politburo Standing Committee who are destined to become the core of the mainland's fifth generation leadership in five years, are PhD holders. Mr Xi has a law degree from Tsinghua University and Mr Li has an economics degree from Peking University. Tsinghua is China's equivalent of the Massachusetts Institute of Technology and Peking University is its Harvard.

New Politburo members Li Yuanchao and Liu Yandong also have PhDs, Mr Li from the Central Party School and Ms Liu from Jilin University.

Several other Politburo members hold master's degrees, compared with virtually none in the previous leadership. Many of the new Central Committee members also hold higher-level qualifications than their predecessors.

Although such degrees are real ones, issued by top institutions, their standard has been widely questioned by some educators because most are obtained through controversial part-time programmes. Almost all the new leaders obtained their higher degrees this way, although many obtained their first degrees through full-time education.

The shortened, part-time programmes for officials have become both popular and controversial.

Universities have incentives to introduce the programmes because they can demand higher fees from officials, who can then claim expenses. The universities also benefit from building connections with top officials and boost their reputations by grooming leaders. But there is also a downside.

'The standard of such degrees, particular PhDs, is questionable as they were obtained on a part-time basis,' said Professor Ma Guoxian , of the Shanghai University of Finance and Economics.

A part-time master's programme usually requires two years of attendance and a part-time PhD programme over three years, the same as full-time study. Professor Ma said it was hard to believe that an official could match the academic achievement of a full-time PhD candidate in three years of part-time study.

Many part-time students are high-ranking officials with heavy workloads supervising a region or industry.

The four PhD holders in the Politburo all obtained their doctorates while they were ministers and provincial governors or deputies, according to their resumes. 'A PhD dissertation requires the author to read hundreds of academic books and do lots of research,' Professor Ma said. 'And such an accomplishment could not be fulfilled through three years of part-time work.'

Party schools have also become popular with officials seeking higher degrees. A party publication once accused such party-run schools of profiteering by providing cadres with substandard courses. The schools are supposed to provide short courses to train cadres to understand the party's thinking and policies, and traditionally they do not offer degrees.

Citing a survey a few years ago, the Xinhua-run China Comment magazine said 92 per cent of party school applicants were incumbent cadres who were studying for diplomas to qualify for promotion.

Many new leaders obtained their degrees from party schools.

Professor Ma and Professor Wan admitted the school authorities and supervising academics often set lower standards for working students.

'We designed shorter courses for officials and often give them tips for exams. Schools often provide the necessary assistance to help such privileged students pass exams,' Professor Wan said, adding that people were happy to provide assistance because it was the best way to cultivate connections.

Skimping on teaching time, abuse of public money and cheating by student officials were widespread, the Xinhua magazine said.

Zhao Shiqing, a National People's Congress deputy who has raised concerns about part-time study on many occasions, has alleged that officials' personal secretaries were often assigned to attend lectures on their bosses' behalf and academic treatises were written by other people.

Professor Zhao from the Anhui University of Science and Technology said some of the students never attended classes.

'A leading cadre in a senior position pursuing a doctorate in our school seldom showed up, much less attended any lectures,' Professor Zhao said. 'Although the academic diplomas are issued by institutions of higher learning, they are, in fact, fake certificates.'

He said senior officials sought doctorates by every possible means because it would 'bring them fame'.

'If they can add the doctorate to their name cards, people may feel that they are not only senior officials but also people with higher learning,' Professor Zhao said.

Professor Ma added: 'It is a kind of education corruption and cheating. And it is also a deep-rooted problem in the mainland's civil service system.'