LONDON — The British government on Tuesday cleared away the last big regulatory hurdle for building the country’s first new nuclear power plant in nearly 20 years. But whether construction will proceed remains uncertain, because the government has not finalized financial terms with the builder, EDF Energy.

The plant, at Hinkley Point in southwest England, is to generate enough electricity for five million homes, and be the first step toward updating Britain’s fleet of nine aging nuclear plants. Edward Davey, the energy minister, said Tuesday that the government had issued a “development consent order” for EDF Energy, a subsidiary of the French energy group EDF, to proceed with construction.

But the government and EDF have not yet agreed on how to guarantee a minimum price for the electricity from Hinkley Point. Mr. Davey said Tuesday that he expected the talks, which he described as “intense,” to “be concluded shortly.”

EDF is seeking a price that would give the company a 10 percent return on the estimated £14 billion, or $21 billion, investment. The government has reportedly been holding out for less. The company may not be inclined to compromise, because other potential builders have dropped out.