Kabul, Afghanistan (CNN) -- Four people have been arrested on suspicion of fraudulent activities during Afghanistan's parliamentary elections, the attorney general's office said Thursday.
Two are suspected of taking money from candidates running for parliamentary seats during the September vote, Deputy Attorney General Rahmatiullah Nazari said.
They had apparently introduced themselves to candidates as European Union observers, "but it's not clear who they were working for and that is what we are investigating at this point," Nazari said.
There was no immediate comment from the European Union.
The two others are believed to be money exchange dealers, he said.
The arrests came the same day the attorney general said his office is investigating allegations of fraud in the elections.
The investigation was launched after both the winning and losing sides filed complaints against the Afghan Independent Election Commission and the Election Complaint Commission, the attorney general's office said.
The spokesmen of both commissions have been suspended over corruption charges and are accused of making statements against Afghan national interests, said Hafizullah Hafiz, director of the complaint commission in the attorney general's office.
Authorities have also arrested a number of people suspected of fraudulent activities -- specifically, having exchanged or planned to exchange money for votes, Hafiz said.
Officials on Wednesday announced results from all but one of Afghanistan's 34 provinces.
Votes from more than 3,000 polling stations were thrown out because of suspected fraud, but the final results will stand, said Fazal Ahmad Manawi, who heads the Independent Election Commission.
The 11 seats allocated for Ghazni province have yet to be finalized, said the commission's Zekria Barakzai.
Ghazni remains unresolved because a deteriorating security situation kept voters in many parts of that province from casting a ballot in the September 18 elections. Barakzai said the election commission will decide the status of the Ghazni seats next week.
It is not known yet which one of Afghanistan's ethnic groups, including the Pashtun-speaking majority, won the most seats in the Wolesi Jirga, the lower house of the National Assembly.
The United States welcomed the certified election results, saying that despite irregularities, the election commission and the Electoral Complaints Commission "have worked well to advance a credible process."
Journalist Matiullah Mati and CNN's Samson Desta contributed to this report.