A group of international investors will appeal against a ruling by an Oslo court regarding Norway's decision to cut natural gas pipeline tariffs, a decision the investors said would cost them 15 billion crowns ($1.8 billion) in lost earnings by 2028.

Challenging Norway's reputation as a predictable place to do business, four firms owned by funds including Allianz, UBS, the Abu Dhabi Investment Authority and the Canada Pension Plan Investment Board, argued that Norway illegally cut fees on the 8,000-km Gassled gas pipeline network.

Solveig Gas, Njord Gas Infrastructure, Silex Gas and Infragas, which hold a combined 45 per cent stake in Gassled, were appealing, Solveig Gas said in a statement to the London Stock Exchange.

Infragas and Njord Gas Infrastructure would continue to invest in Gassled in accordance with contractual commitments, but could shy away from new investments, their chief executives said after the companies publicised their decision to appeal.

Njord Gas Infrastructure said that had the tariffs not been cut, it would probably have bought a stake in the 480-km Polarled pipeline, whose construction was completed last month.

The pipeline connects Statoil's Aasta Hansteen gas field to the Nyhamna onshore processing plant.

"There are other projects which typically would have been interesting before (the cut in tariffs), for example Polarled," Njord Gas Infrastructure CEO Birte Norheim told Reuters.

Infragas CEO Knud Noerve said: "When it comes to investments outside of Gassled, it is not something we're looking at for the moment ... That's because of the uncertainty created."

The four firms bought their stakes in 2010 and 2011 from ExxonMobil, Total, Statoil and Royal Dutch Shell.

In September the Oslo district court ruled in favour of Norway, but said the Oil and Energy Ministry had not provided full information to the buyers and sellers regarding how the tariffs could be changed.

The court added that the ministry's officials at the time had been unaware of how easily this could be done.

"The ministry is to blame for this, but following an overall assessment the court concludes that the actions of the ministry's leadership can't be regarded as qualifying negligence which according to the law is a condition for triggering liability," the ruling said.

The losing party in a lawsuit in Norway will most often be told to pay the winner's legal fees. In the case of the Gassled lawsuit, however, the government was partly to blame for the fact it had gone to trial, the court said, ruling that the parties should pay their own legal costs.-Reuters