A South Korean envoy is visiting to improve ties
The North Korean official news agency earlier said that Pyongyang had decided to resume dialogue with America, as long as what it called "groundless slander" was not repeated.
The reactors are being built by the West on the condition that North Korea freezes its nuclear programme.
But last month North Korea threatened to pull out, angered by American claims that it wasn't fully co-operating fully with UN nuclear inspectors.
Also, in January, President George W Bush called North Korea part of an axis of evil, along with Iran and Iraq.
Thaw in relations
White House spokesman Ari Fleischer said the US position had always been to welcome dialogue with North Korea, but he said the president would continue to speak out in a forthright way.
It was earlier confirmed that North Korea had held talks with US officials last month, in a possible thawing of relations between the two countries.
News of the potential breakthrough came as the South Korean presidential envoy, Lim Dong-won, arrived in the North Korean capital Pyongyang for talks aimed at restarting between the two countries.
Lim Dong-won, a former reunification minister, met his North Korean dialogue partner Kim Yong-sun for two-and-a-half hours, but no details were released.
The North Korean announcement said negotiations were being resumed with the Korean Peninsula Energy Development Organisation (Kedo).
Row developing
Kedo, a New York-based consortium, was set up under a 1994 deal to build a nuclear power station for North Korea in return for ending its own nuclear power programme, which the US suspected was being developed to make weapons-grade plutonium.
But construction is behind schedule and a row has developed between North Korea and the US about allowing weapons inspectors to view the old programme.
The three-day visit by Lim Dong-won, a former unification minister, is the first public contact between the two Koreas for months.
Mr Lim said in Seoul that his first round of talks would focus on the timing of a meeting with North Korean leader Kim Jong-il.
Mr Lim has been a key architect of South Korean President Kim Dae-jung's "sunshine policy", aimed at engaging the Communist state with whom Seoul is still technically at war.
North Korea suspended inter-Korean government exchanges last November, angered by what it believed was a hostile policy being pursued against it by the United States - a close ally of the South.
Much is resting on Mr Lim's visit, even though the South Korean Government is playing down expectations.
The BBC's Seoul correspondent, Caroline Gluck, says many in the South are sceptical about this trip resulting in major breakthroughs.