Mumbai, May 20 -- COMEX gold and silver futures extended downside on Wednesday morning in Asia as dollar index regained momentum above 99 mark. The US Dollar Index hovered around 99.4 on Wednesday, trading at six-week highs as escalating tensions between the US and Iran kept inflation concerns elevated and strengthened expectations for possible rate hikes. The prolonged conflict has effectively kept the vital Strait of Hormuz closed to shipping traffic, pushing oil prices higher and adding to inflationary pressures. The yellow metal is currently quoting at $4462.30 an ounce, down 1% on the day. Meanwhile, silver is also down around 1.5% at $74 an ounce, giving up recent gains recorded earlier this month that were fueled by optimism surround...