An international media watchdog has condemned China for sacking three editors who published an advert marking the 1989 Tiananmen Square bloodshed.
The 'ad' is one line in the bottom right hand corner of this photo
On the 18th anniversary of the killings on Monday, an advert in a provincial paper praised the relatives who still campaign for justice for the victims.
It was accepted for publication by a young office clerk who was not aware of its significance, reports say.
The Chinese government forbids any public discussion of Tiananmen.
The tiny advert on page 14 of the Chengdu Evening News read: "Paying tribute to the strong mothers of June 4 victims."
It is thought to have been a reference to the Tiananmen Mothers' Organisation, which is seeking justice for the students gunned down when government soldiers broke up pro-democracy protests on 4 June 1989.
The young woman who accepted the advert phoned back the person who placed it to ask what "June 4" meant and he told her it was the date of a mining disaster, according to Hong Kong's South China Morning Post.
The chief editor and two vice editors were subsequently sacked.
"Those three journalists are innocent victims twice over," the press freedom organisation Reporters Without Borders said.
"They let through this ad, because one of their staff didn't know what happened on 4 June 1989, so relentless is censorship about this episode."
"These journalists have as a result fallen victim to a purge, which is typical of this government."
Two other newspapers were also approached to run the advert, but junior staff checked its wording with their seniors, Reuters news agency reported.
Hundreds of demonstrators were killed when the authorities sent in tanks to Tiananmen Square on 3-4 June 1989 to break up mass protests calling for greater freedoms.
The Chinese authorities have consistently claimed their actions were justified, but suppress any reference to the events.