Soldiers of Iran's elite Revolutionary Guards march during an annual military parade to mark Iran's eight-year war with Iraq in the capital Tehran, 22 September 2007.

The U.S. Treasury imposed sanctions on Tuesday on a multibillion-dollar financial network that supports an Iranian paramilitary force that it said recruits and trains child soldiers for the country's elite Revolutionary Guards.

The announcement came two weeks before the Trump administration reimposes some of the United States' harshest sanctions against Iran, including its oil sector.

The Bonyad Taavon Basij network provides financial infrastructure to the Basij Resistance Force, a paramilitary force that works for Iran's elite Islamic Revolutionary Guard Corps (IRGC), the Treasury said in a statement.

Both Basij groups were targeted by the new sanctions.

"This vast network provides financial infrastructure to the Basij's efforts to recruit, train, and indoctrinate child soldiers who are coerced into combat under the IRGC's direction," said Treasury Secretary Steven Mnuchin.