Journalists at a major Chinese paper, Southern Weekly, have gone on strike in a rare protest against censorship.
The row was sparked last week when the paper's New Year message calling for reform was changed by propaganda officials.
Staff wrote two letters calling for the provincial propaganda chief to step down. Another row then erupted over control of the paper's microblog.
Hundreds of supporters of the paper gathered outside its office on Monday.
Some carried banners that read: "We want press freedom, constitutionalism and democracy".
"The Nanfang [Southern] Media Group is relatively willing to speak the truth in China so we need to stand up for its courage and support it now," Ao Jiayang, one of the protesters, told Reuters news agency.
Police were at the scene but "security wasn't tight", a former journalist of the Southern Media Group told BBC Chinese.
"They tried to ask those holding placards to show their ID cards," he said, adding that many had refused although "there wasn't much argument".
People were continuing to arrive by mid-afternoon when he left the scene, he added.
Southern Weekly is perhaps the country's most respected newspaper, known for its hard-hitting investigations and for testing the limits of freedom of speech, says the BBC's Martin Patience in Beijing.
Chinese media are supervised by so-called propaganda departments that often change content to align it with party thinking.
It is thought that this is the first time that there has been a direct showdown between newspaper staff and party officials, correspondents say.
The row erupted after a New Year message which had called for guaranteed constitutional rights was changed by censors into a piece that praised the Communist Party.
In response, the newspaper's journalists called for the Guangdong propaganda chief's resignation, accusing him of being "dictatorial" in an era of "growing openness".
In two open letters 35 prominent former staff and 50 interns at the paper demanded Tuo Zhen step down, saying the move amounted to "crude" interference.
On Sunday night, a message on the newspaper's official microblog denied the editorial was changed because of censorship, saying the "online rumours were false".
The microblog updates, said to have been issued by senior editors, sparked the strike among members of the editorial team who disagreed with the move, reports say.
Almost 100 editorial staff members have gone on strike, saying the newspaper is under pressure from authorities.
"Not since the time of reform and opening up and the founding of China has there been someone like Tuo Zhen," Yan Lieshan, a retired Southern Weekly editor, also told Reuters.
Searches for "Southern Weekly" on the Twitter-like weibo are being blocked, reports BBCChinese.com editor Zhuang Chen, who adds there is huge public interest in the story.
Posts deemed to contain sensitive words such as the name of the paper or Tuo Zhen are being actively deleted.
In one post on Monday, swiftly removed, a former Southern Weekly reporter asked current editor-in-chief Huang Can: "If the newspaper no longer exists, where shall we pursue our ideals?
"Naive as I was, I firmly believed that it's always better to dance with shackles than to have no right to dance."
Some influential Chinese journalists have had their social media accounts deleted in recent weeks, Agence-France Presse news agency adds.
When asked about the Southern Weekly issue at a regular press briefing last week, a foreign ministry spokeswoman said that there is "no so-called news censorship in China".
How the case is handled is seen as a key test for Chinese officials, installed just two months ago in a once-in-a-decade leadership transition, observers say.
In an editorial on Friday referring to the row, the state-run newspaper Global Times said: "The reality is that old media regulatory policies cannot go on as they are now. The society is progressing, and the management should evolve."
However it also pointed out that "no matter how the Chinese media is regulated, they will never become the same as their Western counterparts".
"The only way that fits the development of Chinese media is one that can suit the country's development path," it said.