Turkey's government has hit back at the European Union after Brussels called for an investigation into alleged irregularities in the country's referendum.
As many as 2.5 million votes could have been manipulated in Sunday's poll which saw a narrow "yes" vote to grant expanded presidential powers, according to observers.
But the EU's call for a probe was blasted as "unacceptable" by Turkish government minister Omer Celik, who urged the bloc to "respect democratic processes".
European Commission spokesman Margaritis Schinas had said: "We call on the Turkish authorities to consider the next steps very carefully, and to seek the broadest possible national consensus in the follow-up to the national referendum."
The Council of Europe, which monitored the referendum, claimed it was an uneven contest as the "yes" side had dominated campaign coverage, with the arrest of journalists and the closure of media outlets silencing other views.
Alev Korun, a member of the group, said monitors had been prevented from entering voting locations in the majority Kurdish town of Diyarbakir and also raised concerns over videos on social media which appeared to show people voting more than once.
He also said a last-minute decision by the Turkish election authority (YSK) to allow ballot envelopes without the official stamp was illegal.
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Mr Korun said: "There is a suspicion that up to 2.5 million votes could have been manipulated.
"These complaints are to be taken very seriously and they are, in any case, of such an extent that they would turn around the outcome of the vote."
The pro-Kurdish opposition Peoples' Democratic Party has said it presented complaints about unstamped ballots affecting three million voters.
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The opposition CHP party has appealed to the Supreme Election Board (YSK) to cancel the result.
On Monday, the Union of Turkish Bar Associations (TBB) reiterated that allowing unstamped ballots was against the law.
In a statement, it said: "With this illegal decision, ballot box councils were misled into believing that the use of unstamped ballots was appropriate.
"The YSK announcement, which is clearly against the law, has led to irregularities, and the prevention of records that could uncover irregularities from being kept."
Turkish President Recep Tayyip Erdogan has dismissed criticism of the referendum.
He refuted concerns raised by international monitors from the Organisation for Security and Co-operation in Europe (OSCE), telling them to "know your place".
Meanwhile, Turkish Prime Minister Binali Yildirim has said rumours of voting irregularities were a vain effort to cast doubt on the result.
He told parliamentarians: "The people's will has been reflected at the ballot box, and the debate is over. Everyone should respect the outcome, especially the main opposition."
A British Foreign Office spokesman said: "We are concerned by the preliminary findings of the OSCE - which included UK observers. We encourage the Turkish authorities to work with the OSCE to address their concerns.
"It is important that Turkey enacts these constitutional changes in a way that sustains democracy, respects the rule of law and protects fundamental freedoms in line with its international commitments.
"As a friend and ally, the UK stands ready to support Turkey in this process."