MOSCOW, March 26 (Reuters) - Kremlin-controlled energy giant Gazprom has acquired a 27.5% stake, formerly owned by Shell, in Russian liquefied natural gas (LNG) producer Sakhalin Energy for around $1 billion, according to a government order.

The government also officially nullified its order a year ago on selling the stake to Gazprom's rival, Novatek, without explanation.

The Russian government said late on Monday that the 27.5% stake in Sakhalin Energy is due to be sold to a company called Sakhalin Project for 94.8 billion roubles ($1.02 billion).

"No reason was given for this switch in buyers, but some commentators speculated that Novatek may have assessed the legal risk to be too high," Moscow-based BCS brokerage said in a note.

The United States in November imposed sweeping new measures against Moscow, including against Novatek-led Arctic LNG 2 project, over the conflict in Ukraine.

Sakhalin Project is fully owned by Gazprom, company filings showed. Gazprom declined additional comments, while Novatek did not immediately respond to a request for comment.

"We cannot comment on matters relating to the Russian Federal Government's Decree process. Shell reserves all its legal rights relating to its 27.5% (minus one share) interest in Sakhalin Energy Investment Company Ltd (SEIC). We have no further comment," Shell said in an emailed statement.

Gazprom owns 50% in Sakhalin Energy located in the southern tip of Russia's Pacific island of Sakhalin. Other shareholders are Japanese companies Mitsui (12.5%) and Mitsubishi (10%).

Following Moscow's decision to send troops into Ukraine in February 2022, Shell said it would quit the project.

The company booked a $1.6 billion impairment related to the Russian LNG project in the first quarter of 2022.

Sources have said Shell believed there was a risk Russia would nationalise foreign-held assets, while Russian President Vladimir Putin has repeatedly said Moscow would retaliate against the United States and its allies for freezing Russian assets and other sanctions.

In June 2022, the Sakhalin-2 operating company was transformed into a Russian entity via a presidential decree.

Shell as well as Mitsui and Mitsubishi were then asked to apply to keep their stakes if they wanted to.

Moscow invited firms interested in obtaining Shell's stake - as well as Exxon Mobil's abandoned share in the sister Sakahlin-1 project - to submit applications to the government.

In 2022, Sakhalin energy accounted for almost 3% of global LNG demand. Its cargoes mainly head to Japan, South Korea, China, India and other Asian countries.

Last year, it produced more than 10 million metric tons of LNG, down from 11.5 million tons in 2022.

($1 = 92.8375 roubles) (Reporting by Vladimir Soldatkin in Moscow, Deep Vakil in Bengaluru; editing by Philippa Fletcher, Alexandra Hudson)