(CNN) -- Crowds gathered at the headquarters of a Chinese newspaper on Monday, in support of a rare protest by journalists against alleged government censorship.
The journalists at the Southern Weekly paper, based in the southern Chinese city of Guangzhou, claim that an editorial calling for political reform was censored by and re-written as a tribute to Communist Party rule.
Photos published by the South China Morning Post and circulated on China's most popular microblogging site Sina Weibo showed dozens of people gathering outside the paper's headquarters, some holding posters calling for press freedom.
One journalist from Southern Media Group, which owns Southern Weekly, told CNN that colleagues joined the protest to express their outrage.
"We stand up now because we were pushed to the limit," the journalist, who asked to remain anonymous, said.
Some journalists have threatened to strike. If it goes ahead, it would be the first time an editorial staff of a major Chinese newspaper has openly staged a strike in more than two decades, the South China Morning Post reported.
The controversy emerged last week when a group of former Southern Weekly journalists said, in an open letter, that a local propaganda chief had dramatically altered the paper's traditional New Year message, according to a translation published by the China Media Project at Hong Kong University.
While newspapers in China are often subject to censorship, the journalists wrote in the letter that the changes were excessive, and took place after editors had signed off on the final proofs.
The letter also said that the official had introduced factual errors.
A spokesperson from the Guangdong government declined to comment on the incident.
The controversy intensified over the weekend after a second open letter signed by prominent scholars from China, Hong Kong and Taiwan called for the local propaganda official to step down.
On Sunday, Southern Weekly journalists disputed a statement released by their employer. The statement from the paper told readers that the New Year greeting was written by a staff member and the online allegations that a propaganda official had interfered in the paper's editorial were false. It also apologized for the errors in the article.
However, Wu Wei, the executive officer for the paper's new media department, said he had surrendered the password to the paper's official microblog account to the newspaper's management.
"I'm not responsible for the statement to be published on that account and whatever is published in the future," he said in a post on his personal Weibo account that was later deleted.
The furor has dented hopes that China's next president, Xi Jinping, might usher in an era of greater openness for Chinese media.
Doug Young, who teaches journalism at Fudan University in Shanghai, said that China's Propaganda Ministry was on guard as the country's new leadership prepares to take the reins later this year.
The alleged censorship at Southern Weekly also comes as Guangdong, the province where the paper is based, gets a new leader. The previous party secretary, Wang Yang, who was promoted, was seen as being tolerant toward the media, Young said.
"Whenever you have a new person coming in the tendency is always towards conservatism," said Young, whose book "The Party Line" examines the role media plays in shaping public opinion in China.
"It's a changing of the guard both in Guangdong and in Beijing."
Online censors deleted all comments added to Southern Weekly's statement and searches for the four characters that make up Southern Weekly's Chinese name have been blocked from Weibo searches since Friday.
However, some photos of Monday's protest outside the paper's headquarters could still be found online.
The Communist Party-backed newspaper Global Times published an editorial on Monday morning that was critical of the Southern Weekly journalists.
"In the social and political environment of today's China, the so-called free media cannot exist," it said.
"Even in Western countries, the mainstream media will not choose to openly confront the government. To do so in China, there will certainly be losers."
To express their support for the paper's journalists, some Weibo users switched their profile photo to a black-and-white image of the newspaper's logo.
This story is based on reporting from CY Xu and Zhang Dayu in Beijing and Katie Hunt in Hong Kong