Global rating agency Standard & Poor’s (S&P) lowered Russia's credit rating Thursday for the second time in a week.

Russia's long-term foreign and local currency sovereign credit ratings were both lowered to 'CCC-', from 'BB+' and 'BBB-' respectively.

"Russia's military conflict with Ukraine has prompted a new round of G7 government sanctions, including ones targeting the foreign exchange reserves of the Central Bank of Russia (CBR)," the agency said in a statement.

"This has rendered a large part of these reserves inaccessible, undermining the CBR's ability to act as a lender of last resort and impairing what had been -- until recently --Russia's standout credit strength: its net external liquidity position," it added.

S&P said the ratings will remain on credit watch negative and warned that they could be lowered further over the next few weeks./aa