U.S. Energy Secretary Rick Perry has approved six secret requests made by American companies to sell nuclear power technology and assistance to Saudi Arabia, Reuters revealed on Wednesday.

Saudi Arabia is seeking to seal a deal on building at least two nuclear power plants.

The U.S., South Korea and Russia are among the countries competing for that deal.

Reuters quoted a knowledgeable source as saying that Perry's authorizations, allow companies to do preliminary work on nuclear power ahead of the deal, but not ship equipment that would go into a plant.

The companies asked that the approvals would be kept secret, the Department of Energy's National Nuclear Security Administration (NNSA) said in a document seen by Reuters.

Many U.S. lawmakers voiced concern that sharing nuclear technology with Saudi Arabia could eventually lead to a nuclear arms race in the Middle East.