HELSINKI, May 3 (Reuters) - Finnish utility Fortum on Tuesday said it would add 2.1 billion euros ($2.2 billion) in pre-tax impairments from its Russian operations to its first-quarter results.

Several Western companies have announced large writedowns in response to Russia's invasion of Ukraine.

Fortum's shares slipped 1.6% in early trading.

Fortum's Russian division operates seven thermal power plants for district heating in Russia, while its Germany subsidiary Uniper has five power plants across the country through its Russian firm Unipro.

Fortum's write-off includes 0.3 billion euros from its Russia segment, 0.6 billion from Unipro and 0.2 billion from Fortum's ownership in Russian power company TGC-1 and in renewables joint ventures in Russia, the company said.

After the writedowns, Fortum's net assets in Russia totalled 3.3 billion euros, the company added.

Fortum said in March it would write off about 1 billion euros from Uniper's receivables from the Nord Stream 2 gas pipeline project that was halted by Germany in response to Russia's invasion.

Uniper posted an adjusted quarterly operating loss of 829 million euros, saying huge swings in energy prices caused its net debt to soar to 1.98 billion euros at the end of March, more than six times higher than at the end of December.

As Germany's largest importer of Russian gas, Uniper said it continued to talks to German government and Russian gas producer Gazprom about how to implement Moscow's demand to pay for gas in roubles.

($1 = 0.9519 euros) (Reporting by Essi Lehto; Editing by Kirsten Donovan and Edmund Blair)