* Cermaq fails to win enough support to buy Copeinca
* Collapse of that deal was key to Marine Harvest offer
* Marine Harvest says may be willing to raise offer (Adds vote, Marine Harvest, Cermaq comment, shares)
By Victoria Klesty
OSLO, May 21 (Reuters) - Norwegian fish farmer Cermaq has failed to win enough shareholder support to buy Peruvian fish feed maker Copeinca, opening the door to a $1.7 billion takeover of Cermaq by bigger rival Marine Harvest .
Most Cermaq shareholders backed the deal to buy Copeinca at a meeting on Tuesday, but the company was short of the two-thirds support it needed. That result sent Cermaq shares sharply higher as investors bet Marine Harvest would now come back with a sweetened offer to secure a deal.
Marine Harvest, the world's biggest fish farmer, said earlier on Tuesday it would be willing to offer $1.7 billion for Cermaq, or possibly more, but only if the company dropped its own $730 million bid for Copeinca.
"We just have to accept the shareholder vote," Cermaq Chief Financial Officer Tore Valderhaug said. "We still think (the Marine Harvest) offer is low but it's positive they say they are willing to raise it."
Salmon farmers have been among the hottest stocks recently as global demand is rising sharply at a time when supply growth is limited and Chile, a top global supplier, is facing renewed signs of disease.
Marine Harvest, which recently purchased a major processing firm, is aiming to create a global fish giant that would be a top player in everything from feed to processing.
Shares in Marine Harvest, controlled by shipping tycoon John Fredriksen, are up 92 percent over the past year, giving it a market capitalisation of about $4 billion, while Cermaq shares are up over 60 percent.
Cermaq shares surged once again on Tuesday, rising to 110 crowns apiece after the shareholder vote, well above Marine Harvest's 105 crown offer and indicating investors expect an improved bid. Marine Harvest shares also rose over 3 percent.
Marine Harvest's initial proposal was rejected by Cermaq's biggest shareholder, the Norwegian state, which has a holding of 43.5 percent.
Marine Harvest, which has not made a formal bid, said it would now need a few days to put its offer together and that it was willing to consider a higher bid.
"We could be prepared to improve both the price and composition of our offer in order to find an amicable solution acceptable to all parties," it said.
The rejection may also be good news for Copeinca itself as China Fishery Group, which had also bid for the firm, said it would be willing to raise its own bid, if Cermaq's shareholders rejected the deal on Tuesday.
Still, a deal between Marine Harvest and Cermaq could be an uphill struggle.
Fredriksen, estimated to be worth $11.5 billion by Forbes magazine, is a controversial figure in Norway, particularly with the centre-left Labour government.
Having traded his Norwegian passport for Cypriot citizenship for tax purposes, he has been moving many of his companies away from Norway's prosperous oil-based economy, prompting some criticism. (Writing by Balazs Koranyi; Editing by Mark Potter)