President Donald Trump's administration is set to extend a waiver in coming days allowing foreign-flagged ships to transport oil and other commodities between U.S. ports, three industry sources familiar with the matter said on Thursday.

The extension will require individual voyages to undergo case-by-case review rather than allowing foreign ships to receive blanket exemptions from the Jones Act, and it could come as early as Thursday, one of the sources said.

The waiver is one of the tools the administration has used to try to lower diesel and gasoline prices, which have been driven higher by the wars in Iran and Ukraine. The Jones Act, a law more than a century old, generally requires goods moved between U.S. ports to travel on American-built, American-owned and American-crewed vessels, and waivers are the main way foreign ships can carry domestic cargo.

The administration last extended the waiver in August until November 15, and it has already been the longest waiver in the history of the law. A White House official said no decision has yet been made on the extension, adding that any announcements will be made directly by Trump or his administration.