By Josh Beckerman 

Fitch Ratings affirmed its investment-grade rating for Russia, while maintaining its negative outlook for the nation.

Downgrades from Standard & Poor's Ratings Services and Moody's Investors Service earlier this year placed Russia's ratings in junk territory. On Friday, Fitch maintained the triple-B-minus rating, on the brink of junk status. That rating has been in place since a one-notch downgrade in January.

Fitch forecasts Russia's economy will contract by 3.5% this year, compared with a January expectation of a 4% contraction.

"Alongside ever-present oil price risks, a worsening in geopolitical tensions remains the biggest risk" to the stabilization of Russia's economy, Fitch said.

Low oil prices, the conflict involving Russian-backed separatists in Ukraine and the weakened ruble are among the factors that ratings firms have cited in their downgrades.

In a report last month, the Bank of Russia said sufficient reserves and flexible monetary policy ensure the country's financial stability for now, but a possible interest-rate increase in the U.S. and unpredictable oil prices keep the central bank ready to intervene.

Fitch said Russia's ratings "balance a strong sovereign balance sheet and low sovereign financing needs against structural weaknesses (commodity dependence and governance risks), high growth volatility and geopolitical tensions."

Write to Josh Beckerman at josh.beckerman@wsj.com