A Western rights group lashed out at China's lack of media freedom and jailing of journalists on Tuesday (August 7), becoming the latest organisation to criticise Beijing in the run-up to the 2008 Olympics. The New York-based Committee to Protect Journalists (CPJ) said China was falling short of its promise to protect press freedom before and during the Olympics, echoing complaints by Reporters Without Borders and Amnesty International a day earlier. China's poor press freedom landscape could hinder visiting reporters covering the Games and may have a lasting negative effect on local journalists once the international spotlight has faded, the group said in a statement. "But the IOC (International Olympic Committee) does have the ability to speak out. It is the international organiser of the games. It made the commitment. It sought a commitment from China, it said it received the commitment. I think there is a major responsibility for the IOC not to substitute itself for the government of China, but to speak out and encourage the government of China to live up to its commitments," said Paul Steiger, chairman of Committee to Protect Journalists. Steiger said in the statement that China was holding at least 29 reporters and editors behind bars because of their work. "In fact on the ground at local levels, Chinese journalists are under tremendous pressure. They are subject to violent attack. They are subject to pressure. While we realise the central government might have a better intention to this, I think they should be able to control and pressure local officials and bring them to justice when they attack journalists working and doing their jobs at a local level," said Bob Dietz, asia programme director of CPJ. China said on Monday preparations for the Olympics, which begin in a year on Wednesday (August 9), were on track, shrugging off concerns about media freedom, food safety and pollution. But at the Reporters Without Borders news conference in Beijing calling for greater media freedom, several journalists were kept from leaving for up to two hours with no explanation. Reporters Without Borders said China had made specific promises when it was awarded the Games that it would improve press freedom and human rights. Meanwhile, Chinese police have detained six protesters who unveiled a banner calling for a free Tibet on the Great Wall, a campaign group said on Tuesday. Video released by the "Free Tibet" activists showed the banner being unfolded from on top of the Great Wall section on Tuesday (August 6) in Mutianyu, located 70 kilometres northeast of Beijing. The banner read "One World, One Dream, Free Tibet" in English and "Free Tibet" in Chinese. China has ruled Tibet with an iron fist since People's Liberation Army troops marched in in 1950 and has vowed to bring economic prosperity to the poor Himalayan region. "One World, One Dream" is the motto for the 2008 Beijing Olympics, which opens in a year's time. The protesters were on the Wall for about two hours before being detained and taken away, the group said. No other details were immediately available and China's Foreign Ministry said it could not comment. Beijing officials have said the Olympic torch will enter Tibet after ascending the southern slope of Mount Everest -- known in China by its Tibetan name, Qomalangma -- in Nepal. In April, China deported five Americans after they unfurled similar banners at the base of Everest.