Supporters of the ruling AK Party are already celebrating as the last of the votes are counted in a controversial referendum.
Turkish PM Binali Yildirim has declared victory for president Recep Tayyip Erdogan although the country’s election commission has yet to announce official results.
On Sunday, Turks took to the polls to vote on constitutional reforms – with a turnout of around 86 per cent.
A "Yes" vote would replace Turkey's parliamentary democracy with an all-powerful presidency and may see Erdogan in office until at least 2029.
The outcome will also shape Turkey's strained relations with the European Union.
With 98 per cent of the votes counted it seems Erdogan has been given permission to shape parliament to his wishes.
According to the agency votes for 'Yes' stand at 51.49%.
President Erdogan wants new powers which will give him a range of new powers
Turkey's pro-Kurdish HDP opposition said an appeal to the High Electoral Board over vote irregularities will be made.
HDP spokesman Osman Baydemir told reporters: "The referendum result is a clear sign that a societal agreement could not be reached. Our co-chairs being jailed, the referendum being held under a state of emergency, and other oppressive measures cast a shadow and legitimacy problem over the vote."
His plans appeared to take a late blow as Turkey's three biggest cities Istanbul, Ankara and Izmir were reported to have voted against him.
President Erdogan can reshape Turkish Government with a referendum win
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Figures showed “no" votes against the changes have narrowly taken the lead.
According to BBC journalist Seref Isler Turkey’s deputy Prime Minister Veysi Kaynak has said: “We didn’t get the amount of Yes votes we hoped for.”
Yet Anadolu Agency is reporting 98.5% of the ballot boxes have been counted – and it looks like a win for the president.
In Greece, the ethnic Turkish Muslim minority has voted against an increase of power.
Reports say 76.75% chose ‘no’.
President Recep Tayyip Erdogan looks set to be granted new powers
The NATO member state has curbed the flow of migrants – mainly refugees from wars in Syria and Iraq – into the bloc but Erdogan says he may review the deal after the vote.
Earlier in the day a crowd chanted "Recep Tayyip Erdogan" and applauded as the president shook hands and greeted people after voting in a school near his home in Istanbul.
His staff handed out toys for children in the crowd.
Voters have turned out in their tens of thousands in Turkey
"God willing I believe our people will decide to open the path to much more rapid development," Erdogan said in the polling station after casting his vote.
"I believe in my people's democratic common sense."
The "Yes" percentage of the vote – which stood at 63 pe rcent after around one quarter had been opened – eased as the count came further west towards Istanbul and the Aegean coast. Broadcaster Haberturk said turnout was 86 per cent.
The opposition People's Republican Party (CHP) said a last-minute decision by the electoral board to accept unstamped ballots as valid votes put the victory in question.
CHP deputy chairman Bulent Tezcan said: "We will pursue a legal battle. If the irregularities are not fixed, there will be a serious legitimacy discussion."
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If Erdogan wins he will become the most powerful president modern Turkey has known in constitutional terms.
A win for Erdogan will represent one of the most dramatic overhauls of the country’s democratic system since the republic was founded in 1923.
The yes vote will also mean Mr Erdogan can abolish the post of prime minister – a role he had in 2003.
In response, the CHP, Turkey’s main opposition party, will contest 60 per cent of the ballots.
Claims have begun to emerge there have been a large numbers of votes without official stamps.
Turkish President Recep Tayyip Erdogan has high approval ratings in Turkey
Erdogan has huge support in his country, shown most vividly in the failed coup attempt of 2016.
Men, women and children took to the streets and stood in front of rogue army tanks to protect Parliament in Ankara.