The Russian ruble extended losses on Tuesday, falling by more than 4 percent to its lowest since December 2016 as investors continued a sell-off of Russian assets amid a new round of U.S. sanctions.

It was the second straight day of losses for the Russian currency following fresh U.S. sanctions imposed on some of Russian oligarchs and their assets.

The ruble was 4.2 percent weaker against the dollar at 63.28 this morning and had lost 4.4 percent to trade at 77.94 versus the euro.

The rising Brent oil prices, benchmark for Moscow's flagship Urals oil pricing, which were up by 1.3 percent in early trading, did nothing to help a recovery for the ruble.

"While the general backdrop remains uncertain and the threat of further sanctions is unclear, we believe the Russian market is near a temporary floor," Alfa Bank said in a note.

"We note that the fundamentals surrounding the Russian market remain mostly unchanged and that Russian equities still provide among the healthiest dividend returns globally. We would thus ignore the current jitters and buy into the current weakness, particularly with dividend season almost upon us."