South Korea and the United States on Tuesday resumed the new round of talks to rewrite a civilian nuclear cooperation accord in South Korea's central city of Daejeon, the Foreign Ministry said.

The talks, the ninth round of this kind, were attended by South Korean Ambassador Park Ro-byug and US Assistant Secretary of State Thomas Countryman as representatives of each side in the following two days.

Diplomatic sources quoted by Yonhap news agency said the two sides have reached a consensus on adopting an amendment to the treaty on cooperation in nuclear energy, coming after Seoul suggested an amendment at previous talks last September to clarify ways of cooperation in the nuclear energy industry.

The amendment will improve the required process in the US for South Korea's export of key parts for building nuclear power plants and encourage cooperation on spent fuel reprocessing technologies, the source said, adding that more details are needed to be discussed.

The two sides will continue talking about Seoul's demand of enriching uranium and reprocessing spent nuclear fuel, which is the major difference between South Korea and the US

South Korea and the US have started a series of negotiations to revise the South Korea-US nuclear energy pact, dubbed the " 123 agreement", since August 2010. The previous pact banned South Korea from using technologies to enrich uranium and reprocess spent nuclear fuel even for peaceful purposes.

However, South Korea demanded cancellation of these bans considering its rising domestic energy requirement and its role as a global nuclear plant exporter. But the US rejected Seoul's requirement citing proliferation concerns.

The treaty had been due to expire this March but was extended for another two years as both sides failed to narrow differences. The two sides then decided to hold this kind of talks every three months to make future progress.