COLUMBIA - A South Carolina agency's first report on the progress of two nuclear reactors shows the cost rising by more than $500 million because of inflation in construction costs.

Environmentalists call the review by the Office of Regulatory Staff disturbing. But agency executive director Dukes Scott says the increase is no reason for alarm.

The review released Wednesday revises the cost estimate for South Carolina Electric & Gas Co.'s part of the reactors near Jenkinsville from $6.3 billion to nearly $6.9 billion. Scott and an SCE&G spokesman attribute the adjustment to unusually high construction costs over the last five years.

The report says if the latest economic conditions continue, SCE&G's overall costs could stay at or below the $6.3 billion estimate. The total price tag has been estimated at $10 billion.