The Fitch ratings agency on Friday revised its outlook for Russia to negative from stable after the United States slapped new sanctions against Russian officials amid the Ukraine crisis.
Russian soldiers patrol the area around a Ukrainian military unit in Perevalnoye, outside Simferopol, on March 20, 2014
"The revision of the outlook to negative reflects the potential impact of sanctions on Russia's economy and business environment," Fitch said in a statement.
"Since US and EU banks and investors may well be reluctant to lend to Russia under the current circumstances, the economy may slow further and the private sector may require official support," it said.
On Thursday, US President Barack Obama announced a new round of punitive measures against 20 Russians, including some of President Vladimir Putin's closest allies, for Moscow's takeover of Crimea, while the European Union also slapped an asset freeze and travel ban on 12 more Russians and Ukrainians.
"The direct impact of sanctions announced so far is minor, but the incorporation of Crimea into the Russian Federation will likely lead the EU and US to extend sanctions further in response," the rating agency said.
"Furthermore, foreign investors may anticipate further official action and restrict Russian entities' access to external financing," it added.
"In a worst-case scenario, the US may prevent foreign financial institutions from doing business with Russian banks and corporates."
On Thursday, Standard and Poor's ratings agency also revised the outlook for Russia to negative from stable, citing economic and financial consequences that US and EU sanctions could have on the country's creditworthiness.