BEIJING (Reuters) -China has agreed to keep rare earth exports flowing to the world as part of a one-year agreement, President Donald Trump said on Thursday shortly after meeting his counterpart Xi Jinping in South Korea.

The agreement, which Trump provided few details about except that it would probably be extended, would "settle" the issue, he said. China has yet to comment on what was agreed by the two leaders in talks, which ran for almost two hours.

"All of the rare earth has been settled," Trump told reporters on Air Force One. "And that's for the world, worldwide, you could say this was a worldwide situation, not just a U.S. situation."

"There is no roadblock at all on rare earth. That will hopefully disappear from our vocabulary for a little while."

Rare earths, 17 elements which play tiny but vital roles in cars, planes and weapons, have emerged from obscurity to become China's most potent source of leverage in its trade war with the United States.

Export controls introduced in April caused widespread shortages overseas, especially for magnets, forcing some automakers to pause production before exports rebounded following deals between Beijing and Washington and the European Union to free up the flow.

China expanded those controls again in October, taking the total number of elements restricted to 12 and adding much of the equipment used to process them.

The expanded controls are set to come into force in early November and it is unclear whether the agreement discussed by Trump covers the full suite of China's rare earth export controls or just the October extension.

U.S. Trade Representative Jamieson Greer, also on the flight, said China would not be imposing its proposed rare earth controls after an understanding between the presidents. He did not comment on controls that are already in place.

(Reporting by Lewis Jackson in Beijing; Editing by Lincoln Feast.)