Key Asian markets edged higher on Tuesday, as cautious investors sought out value-stocks to tide-over lingering fears of a U.S. downturn. Investors were alert for more possible bad news from the U.S. with the Federal Reserve Chairman to testify before Congress on Thursday, on the state of the world's biggest economy. Japan's Nikkei ended flat after a holiday, with gains in high-tech firms offset by falling insurance plays. Hong Kong stocks rose as investors picked up bargain stocks after a sharp fall yesterday. Resource firms outperformed after a bounce in oil prices, with China's top oil producer Petrochina and aluminium giant Chalco both up. Australian shares also clawed higher, buoyed by mining giants Rio Tinto and BHP to reverse previous day's losses. Taiwan stocks fell after a week-long holiday, with investors sensitive to the threat of a U.S. recession or further fallout from the credit crisis. While rating agency Standard and Poors said global...