Singapore said Wednesday that a US request to extradite four Singaporeans linked to the supply of components for roadside bombs used in Iraq will be reviewed by the city-state's judiciary.

The four were arrested on Tuesday after the US sought their extradition on charges of illegally exporting US-made radio equipment to Iran that ended up in roadside bombs targeting coalition forces in Iraq.

Wong Yuh Lan, Lim Yong Nam, Lim Kow Seng, and Hia Soo Gan Benson were accused together with an Iranian who remains at large of illegally exporting 6,000 radio frequency modules from a Minnesota-based company to Iran.

The modules have encryption capabilities and a range that allows them to transmit data wirelessly up to 40 miles (65 kilometres).

At least 16 of the modules were discovered by US forces in Iraq being used in remote detonation systems for improvised explosive devices or IEDs, which the indictment said caused roughly 60 percent of American combat casualties in Iraq between 2001 and 2007.

"The extradition papers submitted by the USA in support of the extradition request are in the process of being served on the four persons or their counsel," the Singapore attorney-general's office said.

"The four persons and their counsel will need to study the papers before a date for the committal hearing is fixed by the Subordinate Courts.

"A date will be fixed for the committal hearing in the Subordinate Courts, to go through the evidence provided by the United States in order for the Court to decide whether there are sufficient grounds to extradite the four persons."

Three Singapore-based companies and an Iranian company were also charged in the indictment.

Charges include conspiracy to defraud the United States, smuggling, illegal export of goods from the United States to Iran, illegal export of defence articles from the United States, false statements and obstruction of justice.

Some of the defendants were also charged in a separate fraud conspiracy involving the export of sensitive military technology to Singapore and Hong Kong -- radio antennas for use in fighter jets.