And in a rare move, scores of reporters covering the Labour Day rally wore black clothes to protest against the censorship, they said.

'The government is using its propaganda machinery to manipulate public opinion. The whole public consultation was very ugly,' said Scott Chiang Ming-hin, vice-president of Macau Youth Dynamics, the protest organiser.

The government plans to add two directly-elected and two indirectly-elected legislative seats - similar to functional constituencies in Hong Kong - to the present 29 seats in the Legislative Council.

It also proposed expanding the chief executive election committee from 300 to 400 people.

The public consultation on the election process for next year's Legislative Council election and the 2014 chief executive election ended last week.

Yesterday's protest was the first such experience for many young people in Macau.

'I cannot tolerate the government for hard-selling what they called a mainstream opinion,' said Kenneth Hong Kai-man, a 25-year-old clerk and first-time protester, adding the proposals were undemocratic.

Lawmaker Au Kam-san said some young opposition groups had emerged in recent years.

'They represented an opposing voice among the youth because most youth groups in Macau are pro-establishment,' he said.

Luis Yu Wai-ying, a spokesman for the Macau Journalists' Association, said the media's distortion of reality was unprecedented.

'We can feel that there is a very big social crisis. We are also worried that the censorship will be more intense,' he said.

More than half of Macau's population opposed the government's proposals, according to a media-commissioned poll conducted by the University of Hong Kong, Yu said.

Protesters singled out TDM, Macau's public service broadcaster, for heavily censoring its coverage of the political reforms debate.

Ava Chan Lai-cheng, a journalist who left TDM recently, said 45 TDM staffers had quit in the past 45 months because of the censorship.

TDM denies the allegations about external influence and censorship.