HONG Kong shares crashed yesterday after one of America's most powerful investment advisers said it was time to sell. The recommendation stunned investors and stock-brokers in Hong Kong because it came from Barton Biggs, the man reputed to have touched off the huge rise when, in late September, he declared himself to be ''maximum bullish'' on China. News of Mr Biggs' apparent somersault sent the Hang Seng Index plunging. At one point it had fallen 341 points to 9,165 before recovering to close down 171.55 points at 9,335.43. Among the worst-hit stocks were Sun Hung Kai Properties, down $1.50, and HSBC Holdings and Cheung Kong, which both lost $1. The falls in Hong Kong followed a big slump in overnight prices of Hong Kong stocks in London as news of Mr Biggs' fresh views on the market leaked out from New York. Last night, prices were again falling in London as trading started. Mr Biggs, a senior Morgan Stanley analyst, has told his clients that he is reducing the proportion of Hong Kong shares in his model portfolio from 16 per cent to 10 per cent, and believed that the rise in prices had been overdone. ''The craziness content about the magic of China is beginning to look like a bubble,'' he said. But only seven weeks ago, Mr Biggs returned from an eight-day tour of the mainland saying it was the best and brightest emerging market story he had ever heard. ''After eight days in China, I'm tuned in, overfed and maximum bullish,'' he had declared. This sort of enthusiasm electrified Hong Kong, which was seen as the obvious way into China's economy. At that time he raised the Hong Kong weighting from 11 per cent to 16 per cent. His comments unleashed a flood of demand for Hong Kong shares, and the Hang Seng Index rocketed 25 per cent. Now, his views are much more cautious, and he is nervous about the political situation in Beijing. ''It is not clear who the winners will be in the struggle for economic policy in China, but signs of either overheating or a hard landing for the Chinese economy would spook the Hong Kong market,'' he warned. However, he added that he still stuck by his forecast that ''some day, China will experience the mother of all bull markets''. But the advice from Mr Biggs to cut back on Hong Kong stocks sparked angry comments from rival brokers as well as investors in Hong Kong. They complained that after encouraging US funds into the market, where they played a principal part in triggering the 25 per cent jump from the end of September, Mr Biggs was now contradicting his earlier advice. But his views were backed by another senior Morgan Stanley analyst, David Roche, who also came out strongly in favour of Hong Kong and China stocks in September. Mr Roche is now warning that China's economy is facing major dangers. These include the problems of financing the country's current account deficit - or the trade gap with other countries. He said that while the statistics suggest all is well, and that there is officially US$18.8 billion (HK$145.15 billion) in foreign reserves and commitments of US$100 billion of foreign direct investments, against a current account deficit of US$9 billion, it was known that when executive vice-premier Zhu Rongji took over the running of the economy, the coffers of the Central Bank were almost dry. He also said he had serious concerns about the prospects for China if the Uruguay round of the General Agreement on Tariffs and Trade were not implemented. The rise in prices in Hong Kong had gone too far, too fast, he said, although the long-term China story was still in place. While many rival analysts agree with Morgan Stanley's concerns, there was bewilderment over the fact that the two could apparently change their views so strongly in the space of just seven weeks.