OSLO (Reuters) - Several wind farm projects in Sweden are under threat due to the government’s decision to reserve more airspace for its armed forces, according to two companies and an industry lobby group.

FILE PHOTO: Windmills are seen in the "Dan Tysk" wind park of Swedish energy company Vattenfall and Stadtwerke Munich (public services Munich), located west of the German island of Sylt in the North Sea, April 27, 2015. REUTERS/Fabian Bimmer/File Photo

In November, the government said its air force had labeled more airspace as low-flying zones in order to protect its operations from the expanding wind power industry.

The move, to avoid planes colliding with wind turbines, has created uncertainty for a number of planned wind farms.

Sweden’s largest utility, Vattenfall [VATN.UL], said the decision affected at least four of its projects, which together could generate around 1 gigawatt (GW) of power.

“Such projects would lose the permits and couldn’t be built,” spokesman Peter Stedt said, referring to two of the projects that have been approved.

In all, some 2.8 GW of planned wind power production could be canceled, according to industry lobby Svensk Vindenergi, equivalent to 42 percent of Sweden’s current wind production.

Around 1 GW of that relates to wind farms with permits, and 1.8 GW to projects awaiting approval, it said.

Eolus Vind, which builds wind farms and has projects under consideration in the affected areas, said it needed more clarity from authorities.

“Clarification is important so that developers do not spend money on projects that have a low chance of being permitted due to the views of the armed forces,” said spokesman Johan Hammarqvist.

The government said projects that have been approved should not be affected.

“Plants that already have permits to build should normally not be affected by the new low-flying areas,” Energy Minister Ibrahim Baylan told Reuters.

Sweden aims to meet its energy needs without producing global warming carbon dioxide by 2040, and defense interests should be balanced with energy targets, he added.

But Svensk Vindenergi said several companies with approved farms will have to reapply for permits because they need to build turbines that are higher than originally planned, and are therefore at risk of being refused.

“Many of the permitted parks have a maximum height of 150 meters. In general, at least 200 meters is needed to reach the wind needed to be able to realize the project with today’s low price on electricity and certificates,” said Hallberg.

Some projects could still be considered in the newly designated areas, the armed forces said.

“In some cases the thorough analysis that is always performed might conclude that a wind power project can coexist in some specific areas,” its press office told Reuters.

According to Svensk Vindenergi, the government’s decision affects 45 percent of Sweden’s territory, up from 30 percent previously.

The energy ministry and the armed forces did not provide their own calculations of the area affected, with the military saying the information was classified.