Iran on Saturday (Aug 22) denounced United States plans to announce new sanctions that could put further strain on the Islamic Republic's economy and have an impact on its most important trading partners, including China.

After nearly six months of war since the US and Israel launched airstrikes against Iran on Feb 28, the sides are not firing at each other but also showing no sign of pursuing peace talks.

Oil shipments are at a virtual standstill in the Strait of Hormuz, with Tehran threatening to strike any unauthorised oil tankers that try to transit the vital waterway, and Iran's economy is already under immense pressure from sanctions.

US Treasury Secretary Scott Bessent is due to hold a press conference at 2pm (6pm GMT) on Monday after threatening "the toughest sanctions in history" on Iran.

Bessent has also urged cooperation with Washington by China, which buys more than 80 per cent of Iran's shipped oil, according to 2025 data from analytics firm Kpler. Beijing has urged diplomacy.

Iran's Foreign Ministry spokesperson, Esmaeil Baghaei, said on Saturday the imminent US announcement of new economic sanctions was an "assertion of extraterritorial sovereignty over every independent member state of the United Nations".

"Such secondary sanctions find no foundation in international law," he said in a post on X.

The secretary of Iran's ​Supreme National Security Council, Mohsen Rezaei, told state television that Tehran would target the interests of countries helping the United States.

"We are telling all nearby countries not to join the US economic war, otherwise we will consider them as enemies," Rezaei said.

US President Donald Trump, who has warned of economic consequences against any country that provides "any type of lifeline to Iran", said on Friday that Washington was observing "what happens" in the conflict.

"They would love to make a deal, but they're not ready to make the right deal, in my opinion," Trump said of Iran.