Demand for U.S. gold and silver bullion coins is still at "unprecedented" high levels almost two months after an historic sell-off in gold released years of pent-up demand from retail investors, the head of the U.S. Mint said on Wednesday.

His comments are likely to allay concerns among some traders that frenzied buying by mom-and-pop investors since mid-April after prices plunged to two-year lows had started to fade.

Their interest has helped prices recover to above $1,400 an ounce, providing key support to prices after institutional investors fled the futures market and exchange-traded funds.

"Demand right now is unprecedented. We are buying all the coin (blanks) they can make," Richard Peterson, acting director of the U.S. Mint, said in an interview referring to the Mint's suppliers.

The Mint, one of the world's largest gold and silver coin producers, may resume making platinum bullion coins after receiving requests from dealers, he said. It stopped making the coins in 2008 due to low demand.