Former US president Bill Clinton says China's economic growth is not a threat and has called the controversy surrounding the failed attempt by mainland energy company CNOOC to buy US oil firm Unocal silly. 'I wanted you to have the thing [Unocal]. We can't expect American investors to be welcome in China and not welcome Chinese investors in the US,' Mr Clinton told an internet industry conference in Hangzhou yesterday. CNOOC, the mainland's third-largest oil producer, withdrew its bid after opposition in the US. Seeking to differentiate his views on China from those of US President George W. Bush, Mr Clinton also played down worries over the mainland's military build-up. 'Once someone else becomes as rich as we are, then whether we have the only big military in the world is their choice, not ours,' he said in a speech at a conference sponsored by mainland e-commerce company Alibaba.com. His comments follow a US Pentagon report released in July on the mainland's military build-up, including the upgrade of its submarine fleet and an increase in the number of long-range missiles to deter Taiwan's moves towards independence. Mr Clinton praised the mainland's economic growth, but warned that it should reduce dependence on exports. America must reduce its trade deficit too, he said, in a swipe at US policy. 'I've always tried to support the growth of China. I've never felt threatened by it. I've always thought it was a healthy thing for the world,' he said. However, he urged the mainland to seek alternative forms of energy since rapid industrialisation had caused environmental degradation at home and added to the threat of global warning and climate change. Mr Clinton said he understood the mainland's drive to secure energy sources overseas, despite US criticism that Beijing was dealing with rogue nations to quench its demand for resources. Speaking about the future of Sino-US relations, Mr Clinton expressed a hope for co-operation, but said that depended on how the mainland chose to define itself. 'I hope we're competing economically and co-operating politically,' he said. 'America's moment as the only economic, political and military superpower is fleeting and we should be using this moment to build the kind of world we would like to live in when we are no longer the only economic, political and military superpower.' Hangzhou was Mr Clinton's third stop in China. Last week, he visited Zhengzhou in Henan to promote an Aids programme and Urumqi in Xinjiang for development talks.