How many languages can you speak? 90pc of Hong Kong under 30s speak Cantonese, Putonghua and English

A growing number of Hongkongers have become trilingual, with more than 90 per cent of residents under 30 now speaking English and Putonghua, according to a study, although English standards lag behind Chinese.

This compares to the 2011 census, which found only about 70 per cent in the same age group could speak the two languages.

The increasing use of Putonghua has also raised concerns, as almost half of the survey respondents believed Cantonese had been at least moderately threatened as the city's main language.

READ MORE: INFOGRAPHIC: A world of languages - and how many speak them

Researchers believed the study showed the government's "biliterate and trilingual" policy had been effective. They said they could not see Cantonese losing its dominance unless there were deliberate policy changes.

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"For Hong Kong people in the 1980s, it was all about learning English, but in the 1990s it was all about Putonghua," said Professor Kingsley Bolton, one of the researchers at the University of Hong Kong's Social Sciences Research Centre. "Now we have a younger generation who are, increasingly, trilingual. The future for Hong Kong appears to be a trilingual society."

The research showed that Cantonese continued to be dominant, with almost all people in all age groups able to speak it.

The survey, commissioned by the government's Central Policy Unit, was conducted by the centre between August 2013 and January this year. Researchers interviewed 2,049 residents aged 15 and above by telephone in Cantonese, English and Putonghua.