WA's Government Employees Superannuation Board (GESB) holds interests in 20 companies domiciled in Russia, public records show.
These include oil and gas companies Rosneft and Lukoil, state-controlled energy giant Gazprom and Sberbank, Russia's largest state-owned bank.
Rosneft has been identified by several global media outlets as a main supplier of fuel to Russia's military.
Its chief executive Igor Sechin, one of Russia's most powerful oligarchs and a close ally of Vladimir Putin, is among the individuals subject to sanctions under the consolidated list maintained by the Department of Foreign Affairs and Trade.
More than 400 Russian individuals and entities have been added to the DFAT list since last week's invasion of Ukraine.
A GESB spokeswoman on Thursday said the fund had a very low exposure to Russian investments, comprising less than 0.1 per cent of total assets.
GESB has about 240,000 public sector members and more than $36 billion in total funds under its management.
She said GESB's investment managers had reduced exposure "in the lead up to, and subsequent to" Russia's invasion of Ukraine.
"The GESB board has been actively discussing and reviewing recent events and supports the approach adopted by appointed investment managers to reduce exposure and divest where practical to do so," she told AAP.
Market Forces executive director Julien Vincent said the investment was "staggering" given the revenue generated by Russia's oil and gas giants was underpinning the invasion of Ukraine.
"GESB's current portfolio of international shares shows exposure to twenty major Russian companies, including five of the biggest oil and gas companies and several banks now the subject of sanctions," he told AAP.
"The Russian state is heavily dependent on oil and gas companies for its revenues - companies that should already be the subject of exclusions from investors on the basis that their business models are driving the climate crisis."
British oil and gas giant BP this week said it would take a hit of up to $35 billion by offloading its 19.75 per cent stake in Rosneft.
Australia's sovereign Future Fund and the country's second largest superannuation fund Aware Super have also flagged they will dump Russian assets.
GESB's environmental, social and governance policy identifies human rights as one of the key factors that should be considered during the investment process.
Excluding a company from investment is "usually a last resort" based on whether its goods are expected to directly cause human death, significant and irreparable environmental damage, gross inequality in society or legal breaches.
A spokeswoman said GESB's investment managers were required to comply with the fund's ESG policy but "a range of considerations" were made regarding investment decisions.
Its responsible minister is Premier and Treasurer Mark McGowan and it is chaired by Jo Gaines, the premier's former deputy chief of staff.