UPDATE 1-US fund KKR in takeover bid for Portugal's Greenvolt, shares jump

(Adds shares rising after suspension, details, background)

LISBON, Dec 21 (Reuters) - A unit of U.S. private equity fund KKR announced on Thursday a full takeover bid for Portuguese renewable energy company Greenvolt, which values the firm at 1.16 billion euros, and said it had already secured a controlling stake via agreements.

Gamma Lux said in a statement it was offering 8.3 euros per Greenvolt share, which is 11.5% above Wednesday's closing price of 7.45 euros and represents a premium of 32.1% compared to the weighted average price over the last six months.

After a brief suspension from trading, Greenvolt shares jumped 11% to 8.28 euros on Euronext Lisbon.

The fund said that the full takeover offer became mandatory after it signed contracts to buy a total stake of 60.86% in Greenvolt from seven shareholders.

Greenvolt's equity is represented by more than 139 million shares. The company produces energy and develops projects in the biomass, wind and solar segments in Portugal, as well as in 15 European markets and the United States.

Gamma Lux said that the acquisition should only be completed after May 31, as it is subject to approval by regulators such as the Portuguese Competition Authority and its counterparts in Romania, Ireland, Britain and Germany.

In the first nine months of this year, Greenvolt's consolidated net profit fell 64.7% to 5.9 million euros from a year ago even as revenues grew 46% to 268 million euros.

It's earnings before interest, taxes, depreciation and amortization (EBITDA) fell 3.3% to 76.9 million euros. (Reporting by Sergio Goncalves, editing by Andrei Khalip)