* Three partners will file a suit early next year
* A fourth one considering its options
* Government says price cut stimulates exploration
By Gwladys Fouche
OSLO, Dec 6 (Reuters) - Three partners in the Gasslednatural gas pipeline will file a lawsuit against the Norwegiangovernment to try to overturn a decision to cut gas transporttariffs, which they say would cost them $6.6 billion in lostearnings over 20 years.
A group of international investors have put $5.1 billioninto Gassled in recent years. They include the Abu Dhabisovereign wealth fund, Swiss bank and France's Caissedes Depots.
In January the previous centre-left government imposed cutsin tariffs the Gassled network charges energy firms to transportgas from North Sea platforms to processing plants in Norway andterminals in Britain, Germany, France and Belgium.
The new centre-right government on Friday confirmed thatdecision, which has disappointed the Gassled partners, who lastweek met with the oil and energy minister to try to convince himto reverse the decision.
"We will challenge the decision in court," Kurt Georgsen,head of Silex Gas, which is wholly owned by Germany's Allianz told Reuters on Friday. "We will submit it as soon aspossible, probably early next year."
Georgsen said his firm would file the suit together with twoother partners, Infragas, owned by Canada's Public SectorPension Investment Board, and Solveig Gas, representing the AbuDhabi Investment Authority, Allianz, and the CanadaPension Plan Investment Board.
"We are extremely disappointed," Knud Noerve, the head ofInfragas, told Reuters.
He noted that leading figures in both parties in thegovernment coalition, the Conservatives and the Progress Party,had said during the election campaign that the decision shouldbe reviewed. Elections took place on Sept. 9.
"Our initial reaction is that this a break of promises made,especially from the Progress Party," Georgsen said.
Neither Georgsen nor Noerve would say whether a suit wouldalso be filed against firms the stakes were bought from - Total, Statoil and Royal Dutch Shell.
The partners would now stick to their contractualcommitments and not invest in future pipeline developmentprojects. Prior to the tariff cut, further investments wouldhave been to buy stakes in the $4.5 billion, 480-km Polarledpipeline once it is completed in late 2016.
"We will stick to what we have to do in our contractualobligations," said Georgsen. "Polarled is not required withinexisting contractual obligations."
A fourth partner in Gassled, Njord Gas, said it was alsoconsidering legal action but had not yet made a decision.
"We are surprised by the decision that they are not willingto look at the tariff regime again," Dan Jarle Floelo, head ofNjord Gas, told Reuters. "We are assessing the situation."
Njord Gas is owned by Swiss bank UBS and France'sCaisse des Depots.
"GOOD FOR EXPLORATION"
Earlier on Friday the oil ministry said the new tariffs,which are up to 90 percent lower in some cases, would bemaintained to stimulate exploration and would benefit Norway'smaturing oil and gas industry.
"Good resource management means that the profits should betaken out of the fields and not the infrastructure," theministry said. "Tariffs on infrastructure are reduced when theassumed rate of return is achieved."
"Lower tariffs will stimulate exploration, development andproduction of oil and gas, enhancing the competitiveness ofNorwegian gas," it added.
The government has argued the tariffs were originally set upto give investors a 7 percent return on assets but the actualreturn was 10 percent in 2012 and seen at 10.5 percent in 2028.
Gassled is 45-percent owned by international investors. TheNorwegian state holds 46 percent via Petoro whilestate-controlled Statoil owns 5 percent. The rest isheld by foreign energy and utility firms.