'The British controlled Hong Kong for 150 years and wanted people to speak English well,' he said in an interview during a visit to Hong Kong to attend the screening of films about famous authors of Taiwan, including himself. 'They did not care about Chinese. The language here is infected by English.

'The situation on the mainland is even worse, with the impact of not only English but also Russian. Ordinary people do not realise how serious the situation is, but those with a good standard of Chinese do. Even scholars use pseudo-scientific terminology that is incorrect Chinese,' Yu said. As an example, he said the phrase 'using mice to do experiments' was a translation from English that incorrectly reflected the English parts of speech. The correct Chinese phrase is , because in Putonghua 'experiment' and 'to do' are both verbs, making the first translation redundant.

'Everyone on the mainland wants to study English. That will produce these mistakes, and these mistakes will be exported as Putonghua becomes an international language,' he said. 'A Westernisation that is too fast and strong has destroyed the natural state of Chinese and become malignant. People with strong feelings should immediately wake up to this and resist it with all their energy.'

One great loss is the decreasing use of cheng yu , the four-character aphorisms in which Chinese is very rich. 'These have existed for thousands of years and are part of the culture. But now many who write Putonghua do not know them or only a limited number. The decline of cheng yu leads to the fading of the language and the shrinking of culture and knowledge,' he said.

On Sunday in Aberdeen, Yu laid a wreath on the grave of Cai Yuan-pei, a former president of Peking University and one of the leaders of the May 4 movement. 'Many people look down on Hong Kong as a cultural desert. But Cai died on March 5, 1940. The funeral was held five days later and all the flags in Hong Kong were at half-mast, the first time a cultural leader had been honoured in a Chinese city.'

Yu himself is a witness to history. The son of an official of the Nationalist Overseas Chinese Commission, he fled with his family to Sichuan to escape the Japanese during the second world war. He returned to Nanjing, and then fled again to Taiwan via Hong Kong after 1949.

In 1992, he returned to the mainland for the first time after an absence of 43 years, and has been invited back frequently to lecture. His books have been published on the mainland. He has made his home in Kaohsiung, southern Taiwan.

'The mainland is my mother, Taiwan my wife, Hong Kong my love and Europe my one-night stand,' Yu said.

While he lived in Hong Kong, he criticised Mao Zedong and the Cultural Revolution. In response, a Hong Kong left-wing newspaper wrote a critique of him that was 200,000 characters long. In the 1990s, the paper's editor apologised to Yu.

'I was fortunate to encounter the war of words in Taiwan. If I had encountered it on the mainland, I would have lost my life. In Taiwan we had a small cultural revolution; in the mainland a big one. In recent years when I went to the mainland, professors asked me why Taiwan was conducting 'desinicisation'. I told them that they taught us how to do it.'