A narrow majority of voters in Sunday's referendum backed the 18-article constitutional reform package, which will transform the country's parliamentary system into a powerful executive presidency.
Opposition parties have complained of a series of irregularities, including an electoral board decision to accept ballots that did not bear official stamps, as required by Turkish law.
Turkey's main opposition party urged the country's electoral board Monday to cancel the results of a landmark referendum that granted sweeping new powers to Erdogan, citing what it called substantial voting irregularities.
Before the announcement, Prime Minister Binali Yildrim said the opposition had the right to file objections but said that calling for street protests was unacceptable.
"The main opposition party not recognizing the results is not an acceptable thing", Yildirim said.
Turkey's government and president should reverse the decision to extend the state of emergency after winning the April 16, 2017 presidential referendum and end the wave of political repression unleashed in the months before the vote, Human Rights Watch said today.
The move had prevented proper records being kept and could have affected the results, the Union of Turkish Bar Associations (TBB) - known as a body opposed to the current Ankara government - said, adding in a statement: "With this illegal decision, ballot box councils [namely, officials at polling stations] were misled into believing that the use of unstamped ballots was appropriate". Another petitioner, Fusun Cicekoglu, 61, said, "I will not accept my "no" vote be voided and I will not accept "yes" ballots cast illegally".
Worldwide election monitors also delivered a scathing verdict Monday on the conduct of the referendum.
A failed coup previous year allowed him to turn up the heat on opposition voices in the run-up to Sunday's vote. Anti-Erdogan campaigners faced physical intimidation and restrictions on their ability to hold rallies and to appear in the news media.
But Turkey's President has insisted that his plans to assume do not make him a dictator and that the changes were not about empowering him.
Sunday's referendum endorsed by a narrow margin the largest overhaul of Turkey's political system since the founding of the republic almost a century ago, giving Erdogan sweeping authority over the North Atlantic Treaty Organisation member-state.
Under the revised constitution, Erdogan will also be able to abolish the post of Prime Minister and will have authority to annul Parliament and declare an election.
Foreign Minister Mevlut Cavusoglu said that Erdogan and Trump would meet in person next month, before a North Atlantic Treaty Organisation summit.
President Recep Tayyip Erdogan will meet Donald Trump in May, the Turkish foreign minister said today, after the U.S. president congratulated the Turkish leader for winning a referendum on enhancing his powers.
Relations between Turkey and Europe's powerhouse nations have come under strain over Erdogan's comments that he would seek the restoration of the death penalty - a move that would sink Turkey's long-stalled bid to join the European Union.