ISTANBUL -- Turkey's justice minister slammed the main opposition party on Saturday for contesting the outcome of Sunday's referendum on expanding presidential powers and said there is no judicial path to reverse the ruling.

In a series of tweets, Justice Minister Bekir Bozdag said all decisions on electoral issues, including complaints and fraud allegations, are in the purview of Turkey's electoral board.

"Applications against the High Electoral Board's decisions cannot be taken to any court or authority, including the Council of State and the constitutional Court," he tweeted. Bozdag said these judicial organs would reject such applications based on Turkish laws.

Bozdag's comments follow an application by the opposition Republican People's Party (CHP) to the Council of State on Friday, seeking to overturn the electoral board's decision that unstamped ballot papers were valid.

International monitors say that the electoral board's decision removed an important safeguard against fraud and was "contrary to law." The board, however, published past rulings on the validity of unstamped ballots.

The controversy on unstamped ballots formed the basis of applications by the CHP and two other opposition parties to annul the referendum, which the electoral board rejected Wednesday with a 10-1 vote.

CHP officials said they would contest the decision at the constitutional Court and if necessary, the European Court of Human Rights.

The justice minister said the CHP was showing contempt for the people's will and tweeted, "No court can undo/change the decisions of the nation."

Unofficial results show Erdogan's "yes" campaign garnered 51.4 per cent of the vote.