The Government defied falling regional markets yesterday to drive the local share market 4.22 per cent higher with some of the most aggressive buying since its intervention began on August 14, brokers said. The Hang Seng Index soared 317.87 points to 7,845.48 despite a weaker yen, mounting concern over emerging markets and losses on Wall Street on Friday. Equity markets fell yesterday in Malaysia, Singapore, Taiwan, the Philippines, Thailand and Indonesia, while regional currencies also weakened. Hong Kong stock exchange turnover was $9.8 billion, the highest for more than two months. Brokers said the Government spent at least $5 billion in the market yesterday as it channelled funds towards a select number of blue-chip issues. The influx of official cash - which the Government said was aiding its defence of the currency board - has boosted the blue-chip index 17.79 per cent since Government buying began. Seapower Securities senior manager Sunny Chan Ho-sun said: '[Yesterday] was a critical moment for the Government because the market was not doing so well in the morning and the rest of the Asia was also in trouble.' Traders said the Government had changed its tactics, feeding some of its buying through a modified list of brokers and focusing on just four Hang Seng Index-constituent stocks, allowing most of the 33 blue-chips to slump. ABN-Amro Asia trading head Glenn Lesko said the Government dominated buying orders in the cash and futures market. 'At least, they are doing a good job of keeping people guessing. They seem to change their tactics every day,' Mr Lesko said. Yesterday's buying came after Friday's 2.77 per cent stock market fall and last-minute 160- point decline in the futures market, which was investigated by the Futures Exchange for trading irregularities. An exchange spokesman said no wrong-doing had been identified. Prudential Portfolio Managers Asia regional director Andrew Look said the Government was determined to push the market higher after Friday's falls. The August futures contract finished 430 points higher at 7,820, with total futures turnover of more than 61,883 contracts ahead of Friday's expiry. Brokers estimated the Government had bought at least 10,000 August and September contracts. Open interest remained above 100,000 contracts as investors continued rolling positions into September, suggesting most key funds were content to extend their stand-off. The Government-inspired gains have prompted derision from some sections of the financial community, with calls for the move to be examined by the Securities and Futures Commission (SFC). Mr Lesko said the intervention was 'the most obvious incident of market manipulation' he had seen in a decade. An SFC spokesman declined to comment on whether the regulator was examining the Government's market activities. 'The market is free to be used by everyone, including the Government, as long as it is used according to the rules and regulations that bind all, including the Government,' he said. The stock market's gains came despite weaker conditions in the local money market. The overnight interest rate rose one percentage point to 10 per cent, while three-month money finished 87.5 basis points higher at 12 per cent. Commonwealth Bank of Australia treasurer Andrew Fung Hau-chung said the market was assuming the Government would be reluctant to allow interest rates to rise given its huge positions in the equity market. Equities buying yesterday focused on HSBC Holdings, Hang Seng Bank, Hongkong Telecom and Swire Pacific - some of the market's biggest stocks.