President Donald Trump lifted US shipping restrictions on storm-battered Puerto Rico Thursday, removing a legal obstacle that had slowed the disaster relief response to Hurricane Maria, the White House said.

White House spokeswoman Sarah Sanders said in a tweet that Trump waived the Jones Act. "It will go into effect immediately," she told AFP.

The 1920 law restricts shipments between US ports to US-owned and crewed cargo ships, thus preventing foreign-flagged ships from delivering relief aid to the US territory.