Silver rallied for the third straight session on Monday, soaring as much as 7.4% to a near six-month peak, after social media posts since last week called for retail investors to flood into the market and pump up the precious metal's prices.

Spot silver hit its highest since Aug. 11 at $28.98 an ounce earlier in the session, and was up 5.7% to $28.53 by 0242 GMT.

Silver, both a safe-haven asset and an industrial metal, has risen nearly 15% since Thursday, when posts began circulating on Reddit urging individual investors to buy silver mining stocks and exchange-traded funds (ETF) backed by physical silver bars, in a GameStop-style short-squeeze.

"This is Asia's response" to all the retail mania, Brian Lan, managing director at GoldSilver Central said, adding, a lot of investors want to take advantage of the situation and make some profits.

Demand for physical silver has more than doubled since Thursday as investors who were on the sidelines bought the metal on worries that prices will shoot up, Lan said.

In a spill over from US markets, silver ETF listed on Tokyo stock exchange jumped more than 10%, while shares of Australian silver explorers jumped between 20% and 40%.

Data from iShares Silver Trust ETF on Friday showed over 37 million shares were created in one day, each one representing an ounce of silver.

Buying an ETF can boost silver prices by increasing the number of shares in the fund and making its operator buy more metal to back them.

Following silver's gains, spot gold rose 0.7% to $1,858.02 per ounce. US gold futures gained 0.6% to $1,861.10.

The gold/silver ratio, which measures the number of silver ounces needed to buy an ounce of gold, fell to its lowest since 2014.

Platinum rose 2.1% at $1,095.41 and palladium gained 0.5% to $2,238.01. Reuters