As of 2 p.m. Moscow time (10 a.m. GMT), the MICEX index had dropped 0.6%, to 1,450 points. The RTS index declined 0.14%, to 1,649 points.
"Closer to midday, blue chips showed a downward trend on news of European stock indexes going down," said Alexei Bystrov, deputy general director of the OLMA investment group.
The ECB's prime rate now is 3%, but some analysts say it could rise by 0.25%.
"If this happens, a slight drop on European and Russian markets is theoretically possible," said Dmitry Golubkov, an analyst with Aton-Line.
At the same time, decline is checked by the rise of raw materials markets: oil futures have started growing again, settling above $70 per barrel, following a new spiral of tension around Iran.
Dmitry Lukashev, an analyst with Zenit Bank, said that if sanctions were imposed on Iran - the UN deadline for Tehran to respond to incentives for it to give up a controversial nuclear program expires today - the oil price could surge to $90 per barrel.