South Korea held talks with North Korea last year on joint development of minerals including rare earths despite high political tensions, it was disclosed Monday.

The Korea Resources Corp (KORES) said its staff visited the North for two rounds of government-approved talks with the National Economic Cooperation Federation in September and December.

At the meetings proposed by Pyongyang the North handed over rare earth samples and KORES officials analyzed their economic value. "However there have been no follow-up meetings," KORES said in a statement.

The South suspended most trade and contacts in 2010 after accusing the North of sinking of one of its warships with the loss of 46 sailors.

Pyongyang denied involvement but went on to shell a South Korean border island in November that year, killing four people.

Rare earth metals are used in the making of smartphones and notebook computers. South Korea has diversified its sources as China, which controls more than 90 percent of global supply, tightens export quotas.

Dong-A Ilbo newspaper said KORES tried to brief the North on the results of its analysis but no further talks had been held since the death of the North's leader Kim Jong-Il last December.

The North has up to 20 million tons of rare earth deposits compared to China's 55 million tons, the daily said.

"Resource development is what the North needs the most and the South can approach this without a political burden," an unnamed South Korean official was quoted as saying.

The impoverished country has allowed Chinese companies to explore its potentially vast mineral wealth, as its dependence on Beijing grows amid a nuclear stand-off with the United States and its allies.

South Korea estimates the total value of the North's mineral deposits at 6,984 trillion won ($6.09 trillion). (AFP)