Duke Energy Corp , the third-largest U.S. power company, is in talks to acquire rival Progress Energy Inc
in a deal worth more than $13 billion that could be announced as soon as Monday, the Financial Times reported on Saturday.

Citing unnamed people familiar with the situation, the newspaper said the stock-based deal could happen at a modest premium to Progress' current market value of $13.1 billion.

Duke spokesman Tom Williams declined comment on the report. Progress did not immediately return a phone call seeking comment.

The companies are hoping to announce the deal before the opening bell on Wall Street on Monday but some details still need to be worked out so the talks could still be delayed or even derailed, the paper said.

Both electricity generating companies are based in North Carolina and serve clients in North and South Carolina. Duke serves some markets in the Midwestern United States and Progress also supplies customers in Florida.

Duke last year lost out on a bid for the U.S. assets of German utility E.ON but its chief executive, Jim Rogers, an industry veteran who has led various utilities in the past 21 years, has widely been seen as hungry to make acquisitions.

(Reporting by Christian Plumb, editing by Philip Barbara)