MINNEAPOLIS (AP) -- A contractor is suing Xcel Energy Inc. alleging $45 million in unpaid cost overruns during an 18-month overhaul of the Prairie Island nuclear power plant near Red Wing.

Charlotte, North Carolina-based contractor Babcock & Wilcox Nuclear Energy contends Xcel Energy has refused to pay the full cost for replacing a pair of massive steam generators at the plant's Unit 2.

The project was completed last December.

Xcel Energy told Minnesota regulators the project cost $285 million.

If the $45 million in disputed charges are added to that, reports say it represents a 16% cost overrun.

An Xcel Energy spokeswoman says the lawsuit is solely about claims for additional payment that the company considers without merit.

She says Xcel Energy will file a response within 20 days.