However, thousands continued to protest Sunday's referendum, which has set into motion the transformation of Turkey's system of government from a parliamentary to a presidential one that would give more power to President Recep Tayyip Erdogan.
Turkey's state-run news agency says the country's electoral board has rejected the oppositions' petitions to annul the referendum on expanding the powers of the presidency.
He said the electoral board's last-minute decision to allow unstamped ballots had prevented proper record-keeping, meaning that it was now impossible to determine how many invalid or fake votes may have been counted.
The YSK released a written statement following the meeting, saying that the board agreed to reject the petitions submitted by the Republican People's Party (CHP), the Peoples' Democratic Party (HDP) and the Patriotic Party to annul the April 16 constitutional reform referendum.
The party said it would not recognize the result and explore every avenue to overturn the result, including applying to the Constitutional Court and the European Court of Human Rights.
Prime Minister and AKP leader Binali Yildirim said Erdogan could rejoin the party he founded in 2001 once official results - expected before the end of the month - were announced.
"We demand the cancelation of this referendum", Bulent Tezcan said, as quoted by AP.
A prosecutor will now consider whether to press charges against Guven.
Meanwhile, observers from the Organization for Security and Cooperation in Europe (OSCE) and the Council of Europe also said earlier this week that "lack of equal opportunities, one-sided media coverage, and limitations on fundamental freedoms" had created an "unlevel playing field" in the vote. "We will follow closely how Turkey behaves on this. From the German government's point of view, Turkey must. clear up the questions that have been raised".
"That the Turkish leadership didn't like the criticism by the OSCE's election observer mission isn't a surprise to anyone", German Foreign Ministry spokesman Martin Schaefer said.
"You can not come to Turkey and interfere in its politics", Cavusoglu said, calling the observer missions' findings "biased".
Erdogan's referendum win heralds huge changes in Turkey, but will narrow margin humble him?
Turkish Foreign Minister Mevlut Cavusoglu said Wednesday that the two leaders would sit down together before a North Atlantic Treaty Organisation summit scheduled for May 29-30 in Brussels.