The rally, which was organised by Maram (Conference Rejecting Rigged Elections), drew tens of thousands of Sunnis and secular Shiites alike.
The protestors claimed that the polls had been rigged and that the Electoral Commission which has thus far said that it is only willing to look into 35 out of about 1,500 complaints was itself involved in tampering with the votes.
The Iraqi National List, led by former Prime Minister Ayad Allawi, and several other Iraqi groups have threatened to carry out fresh protests and strikes unless the complaints were addressed.
Groups close to Allawi, a secular Shiite, have suggested that the United Nations and the Arab League re-examine ballot counting.
Similar protests were held elsewhere in Iraq towns and cities. A large crowd of mainly Sunnis marched in the town of Tikrit, north of the capital, on Tuesday, while another demonstration against Iranian meddling in the Iraq elections was held in the western town of Fallujah on Sunday. The city of Baquba, northeast of Baghdad, also witnessed on Sunday a political protest by more than 1,000 demonstrators against election fraud.
Later on Tuesday, Abdul-Aziz al-Hakim, the leader of the Iran-backed Supreme Council for Islamic Revolution in Iraq (SCIRI), told a joint news conference with Masoud Barzani that the election results could not be invalidated.
The Shiite cleric rejected a new round of internationally supervised elections.
Meanwhile, a survey conducted by the Al-Jazeera website found that more than 84 percent of people did not believe that the preliminary results of the elections were authentic.
