No one was hurt but passengers were alarmed by the mistake in the incident which took place on Thursday evening, the same day that rail officials finally admitted a Chinese-built signalling system caused last week's fatal crash.

The Shanghai Shentong Metro Company apologised on its website on Friday evening for the latest incident, which saw a train veer right when it should have taken a left turn.

At least 40 people died in last Saturday's crash south of Shanghai, which was the worst ever to hit the high-speed train network, raising questions about whether safety had been overlooked in the rush to develop rail routes.

Premier Wen Jiabao, who often travels to disaster scenes, waited until Thursday to visit the accident site, blaming the delay on illness, and for several days authorities refused to speak about the cause of the crash.

China has almost doubled the compensation offered to relatives of those killed in the accident, state media said Friday, after fierce criticism of authorities' handling of the incident.

Bereaved relatives will receive 915,000 yuan ($142,000) -- 415,000 yuan more than the original amount on offer, according to the official Xinhua news agency.

The Sunday Morning Post said that Chinese propaganda authorities issued a censorship order late Friday, banning all coverage of the crash "except positive news or information released by the authorities".

The ban came after state media published rare criticism of the government over its response to the July 23 crash, which killed at least 40, injured almost 200 and called into question the fast expansion of China's high-speed rail network.

"After the serious rail traffic accident on July 23, overseas and domestic public opinions have become increasingly complicated," the order from the Publicity Department of the Communist Party said, according to the Post.

"All local media, including newspapers, magazines and websites, must rapidly cool down the reports of the incident.

"[You] are not allowed to publish any reports or commentaries, except positive news or information released by the authorities."

The sudden ban sent to newspaper and web editors forced the China Business Journal to scrap eight pages of its newspaper, the Post reported, while the 21st Century Business Herald had to scrap 12 and the Beijing News nine.

The papers had planned special coverage to mark the seventh day after the disaster, the report said. The state-run Xinhua newswire was meanwhile forced to warn subscribers not to use an investigative report it had issued.

The apparent ban was the second since the fatal crash, after propaganda authorities a day after the accident forbade local journalists from questioning the official line, according to the US-based China Digital Times.

That order appeared to be widely ignored, with a comment piece in the Communist party mouthpiece, the People's Daily, on Thursday arguing that China "needs development, but does not need blood-smeared GDP".

After Friday's reported order, angry journalists and editors published the spiked pages on the Twitter-like service Weibo, the Post reported, complaining they were forced to concoct other stories to fill the empty pages at the last moment.

"I was ordered to write something to fill up the empty pages at 10pm. At midnight I could no longer control myself and cried," one reporter was quoted by the newspaper as writing.

The Hong Kong Journalists' Association (HKJA) condemned the ban, saying it was not in line with Chinese premier Wen Jiabao's pledge of an "open and transparent" investigation when he visited the crash site last week.

"HKJA is appalled by such a move and demands that the Chinese Communist Party's Propaganda Bureau withdraw this directive and allows the media to report the truth freely," it said in a statement issued late Saturday.

"We urge premier Wen to personally follow up on this issue."

The association -- which represents 500 journalists in semi-autonomous Hong Kong, which enjoys rights not seen on the mainland -- urged media to continue reporting on the crash "so that the whole world will know what is going on".

Analysts last week predicted a clampdown on Chinese state media and possibly also on Weibo, where furious web users have vented their views since the crash.