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By Nick Mulvenney
BEIJING, Aug 8 (Reuters) - A proud China invited the world to the 2008 Beijing Olympics on Wednesday with a dazzling song-and-dance and fireworks display, but cheers and shouts of 10,000 beaming citizens could not mask fears about pollution.
The crowds gathered on the vast Tiananmen Square, overlooked by a giant portrait of Mao Zedong, the founder of Communist China, in front of a brightly lit Gate of Heavenly Peace, exactly a year before the Games begin.
Police, some with sniffer dogs, had to force back the hundreds who milled around the edges hoping to get a glance of the festivities, watched by Chinese leaders and International Olympic Committee president Jacques Rogge.
The most intensely scrutinised preparations for any Games in Olympic history has brought forth a barrage of criticism for China this week on issues such as human rights, press freedom, pollution, food safety and Tibet.
"We welcome athletes, coaches, officials, spectators and journalists to participate in, observe and report the Beijing 2008 Olympic Games," parliament chief Wu Bangguo told the crowd.
Rights groups have accused China of failing to live up to promises of press freedom made when they were awarded the Games in 2001. Six Westerners were still detained a day after unfurling a banner reading "One World, One Dream, Free Tibet" at the Great Wall, the Free Tibet Campaign said in a statement.
China is often criticised for its harsh rule of the Himalayan region it occupied in 1950.
"The world is watching China and Beijing with great expectation," Rogge said. "Athletes also have great expectations and they are all looking forward to competing in the state-of-the-art Beijing venues.
"Beijing and China will not only host a successful Games for the world's premier athletes, but will also provide an excellent opportunity to discover China, its history, its culture and its people with China opening itself to the world in new ways."
He earlier said that some competitions might have to be moved if continuing efforts by organisers to clean up the city's notoriously smoggy air were unsuccessful. "This is an option," he told CNN.
Beijing Communist Party chief and president of the 2008 organisers Liu Qi said Beijing would ensure a safe Games.
"We will ... continually strengthen security measures, improve the city environment and set a solid foundation for a high-level Olympics."
China finally got its chance to express its pride in the most important sporting and cultural event ever held in the country. Celebrations included 2,008 girls playing the zheng, a plucked instrument similar to the zither, in the east city of Yangzhou.
More than a million Beijingers made their way to the city's parks as sunshine broke through the smog for the first time this week. Security was tight as uninvited guests strained to get into Tiananmen Square, where troops crushed pro-democracy demonstrations in 1989 with huge loss of life.
In the end, police brought in reinforcements to keep the crowds back as arc lamps pierced the light haze above and everybody who was anybody in Chinese pop music wowed the crowds.
Zhou Guowei, from the northeastern province of Heilongjiang, tried to get through with his family, but in the end opted for watching the show on television back in his hotel room.
"It looks like my heartfelt wish has come to nothing," he said.
One pensioner, wiping make-up from her face after taking part in a display of traditional folk dancing in a Beijing park, said she was very happy.
"Thirty years ago, we would never have thought that we could host such an event," she said. "China was not strong enough to host the Olympics, but now we are."
Questions about pollution were answered by some with a shrug and the assurance that "it's much better than it used to be".
Censorship has ensured that most people are unaware of critical human rights reports, many of which say China has failed to live up to its promises on press freedom.
Not everybody in the city was wrapped up in the one-year countdown, however. Wang Jingjing, an eight-year-old newly arrived in the capital from a rural part of neighbouring Hebei, said she had never heard of the Olympics.
And in the Indian capital of New Delhi, thousands of Tibetans marched through the streets, shouting slogans and waving flags in protest against China's actions in Tibet. (Additional reporting by Ben Blanchard, Chris Buckley, Ian Ransom and Liu Zhen)