(CNN) -- Iraqi and U.N. electoral officials are examining allegations of fraud in the December 15 parliamentary elections, a U.S. diplomat said Friday.
Meanwhile, Sunni Arab demonstrators turned out in Baghdad to protest electoral problems. News footage showed chanting demonstrators holding banners and posters of the Iraq Accord Front, the top Sunni Arab political coalition. Protesters also took to the streets of Tikrit, Ramadi, Mosul and Samarra, said a spokesman for the Sunni bloc.
Robert Ford, a political adviser at the U.S. Embassy in Baghdad, said the Independent Electoral Commission of Iraq and a U.N. team of advisers are looking into the election complaints.
"It is important that the elections are considered credible by all political parties in Iraq; therefore, we must take the proper steps," Ford said.
Electoral problems prompted secular Shiite and Sunni Arab groups on Thursday to protest the latest partial results in which the Shiite-led United Iraqi Alliance has a commanding lead.
The United Iraqi Alliance is the most powerful party in the transitional government's ruling coalition.
The groups are talking about conducting protests and even boycotting the new parliament, the Council of Representatives, if complaints of fraud are not properly addressed.
Ford said the investigation would delay announcing results but added that "it's more important that the results be credible."
U.S. officials are hopeful that a new government will foster Shiite-Sunni harmony, which has been elusive during the insurgency.
But representatives from Sunni, Kurdish and secular Shiite groups on Thursday rejected the preliminary results, claiming fraud.
Their umbrella group, called Maram, is calling for new elections. The group wants the Independent Electoral Commission of Iraq -- which oversaw last week's vote -- to be disbanded and an alternative set up.
If that isn't done, Maram plans to call for nationwide peaceful demonstrations. Reports indicate a boycott of the new Council of Representatives could be in the works.
Iraqi Prime Minister Ibrahim al-Jaafari said citizens and groups have a right to raise complaints, and those concerns must be reviewed in the legally mandated process that the electoral panel is using.