SEOUL (Reuters) - South Korea has found an undetermined amount of rare earth minerals in a deposit in the eastern Gangwon province, state-run Korea Resources Corp (KORES) said on Monday.

The discovery came amid lingering tension over China’s controls of its rare earth supplies, which account for 97 percent of global output.

The United States and Japan, in particular, have been calling for China to loosen its export constraints for the minerals that are used in high-tech products from electric cars to LCD televisions to new energy technologies.

“We have to get ready to be self-sufficient in case China strengthens its control over (rare earth) exports,” a KORES spokesman said.

China has sought to reassure its trade partners. It will maintain its exports of rare earths next year, Chinese Trade Minister Chen Deming said on Friday, adding that the trade issue should not be allowed to become a political issue.

China cut back its 2010 exports quota of rare earths by 40 percent from 2009 levels, which caused prices of the minerals to soar and made it more cost effective for other countries to start searching for their own supplies.

The South Korean state-run mining firm discovered veins containing rare earths while re-developing an iron ore mine. KORES said it would proceed with exploration to determine the quantity and make up of the mineral deposit.