South Korea is considering ways to extend its atomic energy cooperation pact with the United States due to difficulties in reaching an agreement on the accord's amendment, a government official said Sunday.

Revising the civil nuclear cooperation agreement is one of the most urgent and thorniest issues between the two nations. The so-called 123 agreement, signed in 1974, expires in March next year. Given the time for domestic procedures, Seoul and Washington need to reach a deal by the first half of this year.

The South Korean government is, however, reviewing ways to extend the existing pact by one or two more years as the country may need to take more time to iron out issues with the pact. 

"The new (Park Geun-hye) administration has not even started any talks on the pact," the official said. "A successful outcome cannot be made in one or two months and hasty decisions (on the

pact) should be avoided so as not to have a negative impact on Seoul-Washington relations," the official said, indicating the countries may take more time before renewing the accord.

The current agreement on commercial nuclear cooperation bans South Korea from reprocessing nuclear waste from about two dozen reactors that use U.S.-supplied nuclear materials. South Korea, a major nuclear energy developer, wants the U.S. to allow it to adopt a proliferation-resistant technology for enriching uranium and reprocessing spent atomic fuel from its nuclear power plants.

The Obama administration, however, takes a dim view of Seoul's push in light of Washington's nonproliferation campaign.

Washington is apparently worried about the possibility that South Korea's expansion of its nuclear program will create a domino effect.

Experts have said it may be hard for the two countries to strike an agreement in the next three months due to their diverging opinions over the bilateral pact. 

Another source well-versed in the issue said both countries are now unwilling to budge. "Both South Korea and the U.S. have not changed their initial stances over key issues," the source said.

Seoul is also reluctant to show any signs of discord with the ally ahead of a South Korea-U.S. summit meeting in the first half of this year. 

In addition, the importance of a close alliance between the countries is increasingly important amid growing tensions over North Korea's nuclear test last month. 

Experts said Seoul may make a decision on the extension option following the Seoul-Washington foreign minister talks slated for late March or early April. (Yonhap News)