Proposals for Guangdong's main TV company to broadcast in Mandarin have angered citizens in the province

A Chinese "culture war" has spilled onto the streets of a southern city as hundreds of inhabitants held an unusual mass rally to defend their local language.

Proposals for Guangdong's main television company to broadcast primarily in Mandarin – China's official language – have angered citizens in the province, who fear that Cantonese is being sidelined.

Some worry that Cantonese, which is also spoken in some other parts of the mainland, Hong Kong and Macau, is on its way to extinction. According to the official People's Daily newspaper, it is the first language for half of the 14 million residents of the provincial capital Guangzhou, while the other half speak mainly Mandarin.

Up to a thousand protesters gathered in the centre of Guangzhou shouting slogans, before police dispersed them peacefully. A witness said most were in their twenties, although some were middle-aged.

The controversy broke out when the local committee of the Chinese People's Political Consultative Conference – a political advisory body – urged authorities to ensure that Mandarin, which is spoken across the country, is used on Guangzhou TV's main shows. It said the move would promote unity and help tourists and athletes who will arrive in the city for the Asian Games this November.

Although the network has said it will continue to broadcast in both languages, residents fear that Cantonese is being squeezed out and could ultimately be dropped completely. They argue there are already plenty of Mandarin channels for people to watch and say that a decline in the use of the language will also erode the area's cultural heritage.

In a poll on the committee's own website, 80% of the 30,000 respondents said Guangzhou TV stations should broadcast in Cantonese.

The English edition of the official newspaper The Global Times described the row as a "culture war". It reported that the company spent 30m yuan (£3m) switching its business channel to Mandarin last year, only to see ratings drop.

"Promoting Mandarin does not mean Guangzhou has to eliminate its dialect," Su Zhijia, the city's deputy Party secretary, told China Daily. "The city government has never had such a plan to abandon or weaken Cantonese."

He praised local culture, but said that residents should improve their Mandarin and use it on formal occasions and in public places, reflecting the government's policy of promoting it.

The influx of workers from other areas of China has been perhaps equally important in Mandarin's ascendance in the area – although some migrant teenagers are said to have adopted Cantonese because they think it is more fashionable.

Last year, Lu Hanen, a local campaigner, told the South China Morning Post: "I don't think we can stop Cantonese from being eliminated, but I want to slow [the decline]."