(Reuters) -London aluminium prices were flat on Monday as market players weighed risks of a major trade war after U.S. President Donald Trump said he was set to impose new 25% tariffs on all steel and aluminium imports.

Three-month aluminium on the London Metal Exchange (LME) was little changed at $2,628.5 a metric ton, as of 0600 GMT, after two straight sessions of gains.

The aluminium contract on the Shanghai Futures Exchange (SHFE) was 0.2% higher at 20,525 yuan ($2,809.14) a ton, after hitting its highest level since early December 2024 on Friday.

On Sunday, Trump said he would introduce new 25% tariffs on all steel and aluminium imports into the United States, which would come on top of existing metals duties, in another major escalation of his trade policy overhaul.

Trump said he would announce reciprocal tariffs on Tuesday or Wednesday, to take effect almost immediately, applying them to all countries and matching the rates levied by each country.

Australia's trade minister said the country's steel and aluminium exports to the United States create "good paying American jobs" and are key to shared defence interests, as Canberra presses Washington for an exemption to the planned tariffs.

"While steel and aluminium appear to account for a larger share of U.S. imports from Taiwan, Korea and India, we estimate the exposure to be only around 5% of their shipments to the U.S., at most," Barclays said in a note.

LME copper fell 0.2% to $9,390 a ton, zinc held steady at $2,841, tin eased 0.2% to $31,060, lead was steady at $1,992.5, and nickel traded unchanged at $15,760.

SHFE copper gained 0.5% to 77,140 yuan, nickel firmed 0.1% to 127,180 yuan, zinc fell 0.1% to 23,785 yuan, lead gained 0.4% to 17,160 yuan and tin rose 0.2% to 258,670 yuan.

($1 = 7.3065 yuan)

(Reporting by Anushree Mukherjee and Anjana Anil in Bengaluru; Editing by Eileen Soreng and Subhranshu Sahu)