South Korea has signed a 3 trillion won (NZ$3.61 billion) contract with a Russian state-run nuclear energy company to provide components and construct turbine buildings for Egypt's first nuclear power plant, officials said.

The South Koreans hailed the deal as a triumph for their nuclear power industry, although it made for awkward optics as their American allies push an economic pressure campaign to isolate Russia over its war on Ukraine.

South Korean officials said the United States was consulted in advance about the deal and that the technologies being supplied by Seoul for the project would not clash with international sanctions against Russia.

According to South Korea's presidential office and trade ministry, the state-run Korea Hydro and Nuclear Power were subcontracted by Russia's Atomstroyexport to provide certain materials and equipment and construct turbine buildings and other structures at the plant being built in Dabaa. The Mediterranean coastal town is about 130km northwest of Cairo.

Atomstroyexport, also called ASE, is a subsidiary of Rosatom, a state-owned Russian nuclear conglomerate. The company has a contract with Egypt to deliver four 1200 megawatt reactors through 2030. Korea Hydro and Nuclear Power's part of project is from 2023 to 2029.

A senior aide of South Korean President Yoon Suk Yeol said the negotiations were slowed by "unexpected variables", mainly Russia's war on Ukraine and the US-led sanctions campaign against Moscow over its aggression.

Choi Sang-mok, Yoon's senior secretary for economic affairs, said South Korea provided an explanation to the United States in advance about its plans to participate in the Dabaa project and that the allies will maintain close consultation as the work proceeds. As part of US-led sanctions against Moscow, South Korea has ended transactions with Russia's central bank and sovereign wealth funds and banned exports of strategic materials to Russia.

Neither Choi nor officials from South Korea's trade ministry elaborated on how the crisis in Ukraine and the sanctions on Moscow affected the negotiations between Korea Hydro and Nuclear Power and ASE.

Choi stressed that South Korea's involvement in the project would not clash with international sanctions against Russia.

"Any kind of issue can be met by various uncertainties, but those have all been resolved as of now, and that's why we were able to finalise the agreement," he said.

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Yoon's office expressed hope that South Korea's participation in the Dabaa project would help the country gain a foothold in future nuclear projects across Africa and also improve its chances to export to countries such as the Czech Republic, Poland and Saudi Arabia.

Korea Hydro and Nuclear Power had been engaging in negotiations with ASE as the preferred bidder for the turbine-related project since December, before Russia's invasion of Ukraine in late February.

- Kim Tong-Hyung, AP