April 19 (Reuters) - A unit of Thai company SCG Chemicals PCL has agreed to pay $20 million to the United States to settle potential civil liability for violations of U.S. sanctions on Iran, the Treasury Department said on Friday.

SCG Plastics Co shipped high-density polyethylene resin but hid the product's Iranian origins, causing U.S. financial institutions to unwittingly process $291 million in wire transfers that contravened the sanctions in 2017 and 2018, the department said in a statement.

"As a result of these transactions, significant economic benefits were conferred to Iran's petrochemical sector, a major source of revenue generation for the Iranian regime," it said.

(Reporting by David Ljunggren, editing by Paul Grant) Keywords: USA IRAN/SANCTIONS THAILAND