Vladimir Putin's United Russia party won 20% points less than the officially announced figure of just under 50%, a Russian election monitoring group said on Thursday.
The Internet group Citizen Observer (nabludatel.org) said United Russia had received only 29.8% nationwide, and 25.8% in the Russian capital.
Their figures also gave the liberal Yabloko party enough votes to have won seats in parliament, which was denied them under the official results.
The group, which based its figures on 176 polling stations where its observers were able to make an alternative count, also contested the official turnout figure. The real voter turnout much lower than the official figures, it said.