* Bid conditional on Cermaq's dropping Peruvian offer
* Would pay 50 pct with cash, rest with stock
* Norwegian govt holds 40 pct of Cermaq
OSLO, April 30 (Reuters) - Marine Harvest, the world's biggest fish farmer, said it would buy rival Cermaq in a deal worth $1.69 billion if it abandoned plans to buy Peruvian fishmeal firm Copeinca.
Marine Harvest, controlled by shipping tycoon John Fredriksen, said it would pay 105 crowns ($18.24) per Cermaq share, 22 percent above its close on Tuesday, but only if Cermaq dropped its offer, which values the Peruvian firm at about $732 million.
Norway's fishing firms have enjoyed a boom this year as soaring product prices and strong consumer demand have driven up profits and stock prices. Marine Harvest's shares have more than doubled over the past 12 months.
On Tuesday the company lifted its guidance for return on capital employed and said it would list its shares in the United States.
Marine Harvest said that Cermaq's proposed fishmeal acquisition would be the wrong kind of market exposure and that instead it wanted to create an integrated protein company emphasizing feed, farming and value-added processing.
Marine Harvest said it would pay half in cash and the rest with stock. To emphasize its intent, it also launched a 350 million euro convertible bond offer on Tuesday.
Although the Norwegian government holds 40 percent of Cermaq and a deal would require its blessing, it has said in the past that a sale was not out of the question.
Cermaq said it would respond to the offer on Thursday, while Norwegian government officials could not immediately be reached for comment.
Marine Harvest shares closed up 2.3 percent on Tuesday, while Cermaq shares closed unchanged at 86 crowns.