The validity of the vote - which will do away with Turkey's parliament and could allow Erdo─čan to stay in power through 2029 - was challenged by the opposition party and worldwide election observers.

Declining to congratulate the Turkish president, the European Union executive's second official response since the vote instead focused on observer findings that the vote was skewed in Erdogan's favor without a proper legal framework and with late changes in ballot counting.

19 for three more months, with the parliament's approval, the government spokesperson Kurtulmus said after a cabinet meeting chaired by President Recep Tayyip Erdogan.

Legislator Utku Cakirozer told The Associated Press that his Republican People's Party would on Monday file objections to results at local electoral board branches, before taking their case to the Supreme Electoral Board.

News of the call comes as opposition groups in Turkey have contested the results of the referendum. The ministry called it "unacceptable" and accused the OSCE of political bias. "If the people approved it that way, everyone has to respect it. Let's wish for the best".

Kilicdaroglu said the referendum result was not only a success for his party, the CHP, but everyone who defended democracy.

Protests were held in several locations across Istanbul and in the capital, Ankara, over the handling of the vote; similar demonstrations were reported in other cities.

"With this illegal decision, ballot box councils [officials at polling stations] were misled into believing that the use of unstamped ballots was appropriate", the Union of Turkish Bar Associations said in a statement. We will not consider, see or recognize your political report. The change has raise concerns of "ballot-stuffing" - where extra votes are cast illegally to manipulate results.

Erdogan lashed back at the global monitors' initial findings, telling them to "know their place", Reuters reported. But "the space for dissent is much, much more restricted now", Fahim says. "No" campaigners in the region said its observers were prevented from monitoring many ballot stations. The OSCE also said its monitors faced restrictions.

Opposition parties have promised to challenge the outcome.

At the White House Monday, Press Secretary Sean Spicer said that the administration meant to "wait and let [the global commission reviewing the vote] do their job", when asked if Trump was "concerned" about the results. "It's a complication for Erdogan, but he will try and turn it to his advantage by saying the West is up to its old tricks again".

To be sure, the strength of Turkey's democratic norms were already eroding, but the point of the referendum was to shift away from the country's parliamentary system, putting even more authoritarian power into Erdogan's hands.

Erdogan's margin of victory was razor-thin, and there were strong indications that the vote was far from fair.

Trump's congratulatory message strikes a different tone to the statement issued by the US State Department, which urged Erdogan to "protect the fundamental rights and freedoms of all its citizens".