Gold, silver and platinum rallied to one-month highs on Tuesday as concerns over the outcome of the U.S. election sparked losses in stocks and the dollar, prompting investors to seek out precious metals as a haven from risk.
The announcement of an FBI investigation into Hillary Clinton's use of a private email server during her time as Secretary of State helped send the so-called "fear index" of market volatility to its highest in a month on Tuesday, fueling risk aversion.
Opinion polls show Democrat Clinton's lead over Republican Donald Trump has narrowed slightly since early last week.
"The Trump risk seems to be back in the market at least to some extent," Commerzbank analyst Carsten Fritsch said. "One common factor is certainly the weaker dollar today." A Trump win would likely boost gold due to uncertainty over U.S. economic and foreign policy, HSBC said in a note, citing also a protectionist slant to Trump's policies and his commitment to tax cuts, which are expected to increase the federal deficit.
The dollar fell 0.6 percent against the euro and stocks were on the back foot going into the final days of a fractious U.S. presidential campaign.
The two-day Federal Open Market Committee meeting starting later on Tuesday will also be closely monitored for clues on the timing of a possible U.S. interest rate hike.
Gold is highly sensitive to rising U.S. interest rates, as these increase the opportunity cost of holding non-yielding bullion, while boosting the dollar, in which it is priced.
Markets were pricing in around a 78 percent chance the Fed will raise rates in December, but just a 6 percent chance of a hike this week, according to the CME Group's FedWatch Tool.
"We still have to see what will happen with the Fed," Capital Economics analyst Simona Gambarini said. "It's unlikely that much will happen this week -- it's reasonable to expect that it will wait until December to hike rates."
With the prospect of a Fed rate hike explicitly tied to the strength of the U.S. economy, traders are also keenly awaiting U.S. non-farm payrolls data for October on Friday.
Silver was up 2.8 percent at $18.37 an ounce, having peaked at $17.88, while platinum was up 1.4 percent at $990.41 an ounce, off an earlier one-month high of $996.10. Palladium was up 1.8 percent at $629.40.