Updated

The Latest on Turkey's referendum on boosting presidential powers (all times local):

9 p.m.

Turkey's electoral authority has released the official tally of the referendum on expanding presidential powers, confirming a narrow win for President Recep Tayyip Erdogan's "yes" camp.

Sadi Guven, the head of the High Electoral Board, told reporters that the "yes" side received 51.41 percent of the votes in the April 16 referendum, while the "no" votes garnered 48. 59 percent.

Guven said: "our board declares that the constitutional amendments have been accepted."

The opposition contested the April 16 referendum on the grounds that the decision to count ballots without the official stamps was illegal and allowed for fraud.

___

8:45 p.m.

Turkey's electoral authority has justified its decision to validate unstamped ballots cast during the country's referendum on boosting presidential powers, citing a duty to protect citizens' right to vote.

The opposition contested the April 16 referendum which gave President Recep Tayyip Erdogan's "yes" camp a narrow victory, on grounds that the decision to count ballots without the official stamps was illegal and allowed for fraud.

The High Electoral Board rejected the opposition appeal last week. In its formal justification released Thursday, it said the decision was taken to ensure that voters' ballots were not invalidated due to polling clerks' mistakes.

It said there was no evidence of fraud and rejected claims that the decision was illegal.

Turkey's main opposition party will take its appeal to the European Court of Human Rights.

___

2:10 p.m.

German Chancellor Angela Merkel says that Germany is closely watching to see how Turkey will respond to reports from international election monitors who noted a series of irregularities in a referendum to increase powers for President Recep Tayyip Erdogan.

Organization for Security and Cooperation in Europe monitors found many votes could have been manipulated in the close vote that went in Erdogan's favor, and Merkel told Parliament the Turkish government "must answer the questions" raised.

Merkel says that "we will follow very closely how Turkey deals with the reports."

She also accused Turkey of holding journalists without grounds, including German-Turkish reporter Deniz Yucel, who was detained earlier this year.

Merkel says that Germany will talk with EU partners about "which precise consequences are appropriate and at what time."