MANILA: Dalian iron ore tumbled to a three-week low on Thursday, while prices of the steelmaking ingredient were volatile in Singapore, pressured by nagging worries about weak steel demand and rising supply in China.

A record-breaking heatwave gripping several regions in top steel producer China since mid-July has caused power shortages, forcing authorities to ration electricity with residential use prioritised over industrial consumption.

Some steel mills have reportedly been ordered to halt or curb operations and steel demand has also been dampened in the short term, analysts said.

Iron ore’s most-traded January 2023 contract on China’s Dalian Commodity Exchange fell as much as 4% to 678 yuan ($99.97) a tonne, the lowest since July 27. On the Singapore Exchange, the front-month September contract was down 0.2% at $101.45 a tonne, as of 0245 GMT.