The Turkish referendum that gives President Tayyip Erdogan sweeping new powers fell short of European standards, international observers say.
Turks on Sunday voted by a narrow 51.4 percent margin to change their constitution and grant Mr Erdogan extended powers. The main opposition party has demanded the result be nullified, saying the voting was marred by irregularities.
Restrictions on media outlets, arrests of journalists, inadequate legal framework and late changes in ballot counting were cited by the Parliamentary Assembly of the Council of Europe that monitored the vote.
"Generally speaking the referendum fell short of CoE standards ... it did not provide for a truly democratic process," Cezar Florin Preda said.
Turkey's High Electoral Board made a last-minute decision on Sunday to count ballots that had not been stamped by officials.
The US State Department says it has taken note of the concerns and looks forward to a final report, suggesting it will withhold comment until a full assessment is completed.
Turkish Prime Minister Binali Yildirim said on Monday that the people's message was clear after a referendum and the vote had ended all arguments.
Turkey's foreign ministry meanwhile denounced election observers' criticism that the referendum fell below international standards, saying their remarks lacked objectivity and impartiality.
A mission of observers from the 47-member Council of Europe, the continent's leading human rights body, said the referendum was an uneven contest.
"Saying the referendum fell below international standards is unacceptable," the ministry said in a statement, adding that previous "politically charged" comments from OSCE monitors showed the team arrived in Turkey with prejudice and disregarded principles of objectivity and impartiality.