ISTANBUL (AP) " The Latest on the outcome of Turkey's referendum (all times local):
Demonstrations against the outcome of a referendum expanding the president's powers are continuing in Istanbul, where protesters are demanding the resignation of the election board that has refused to void the vote.
About 2,000 protesters gathered in Istanbul's Besiktas neighborhood on Wednesday evening over the referendum approving constitutional changes sought by President Recep Tayyip Erdogan.
The demonstrations began in smaller numbers after Sunday's vote with clattering pots and pans, but have since drawn thousands of participants expressing outrage at alleged voting irregularities.
The protesters on Wednesday evening chanted "Thief, Murderer, Erdogan" and "Don't be silent, shout out, 'no' to the presidency."
Turkey's state-run news agency says 19 people were detained in Istanbul for allegedly using the results of a constitutional referendum as an "excuse" to organize "unauthorized demonstrations."
Anadolu news agency cited a statement by Istanbul Police that said the suspects were detained early Wednesday for attempting to provoke a response similar to the mass anti-government demonstrations that happened across Turkey in 2013.
Those protests were sparked by plans to uproot trees in Istanbul's Gezi Park to build a shopping mall.
Thousands have been protesting in major cities since Sunday's referendum, which has set into motion the transformation of Turkey's system of government from a parliamentary to a presidential one.
A member of Turkey's main opposition party says the party plans to go the country's top court to challenge the electoral board's 10-1 decision to uphold the results of the referendum expanding the president's powers.
Mehmet Hadimi Yakupoglu, the Republican People's Party's representative to the High Electoral Board, said the party had asked the board to annul Sunday's referendum "because we weren't able to ensure election safety."
The board met for seven hours Wednesday before rejecting the request.
Yakupoglu says his party won't give up on "no" voters who opposed the changes and whose ballots were estimated to account for 48.6 percent of those cast.
He says the party's next stop is Turkey's constitutional court and, if it is unsuccessful there, then the European Court of Human Rights.
Turkey's state-run news agency says the country's electoral board has rejected the oppositions' petitions to annul the referendum on expanding the powers of the presidency.
The Anadolu news agency reported Wednesday that the High Electoral Board voted 10-1 against the decision.
Opposition parties filed formal requests Tuesday to void the results over voting irregularities, particularly an electoral board decision to accept ballots without official stamps, as required by Turkish law.
Turkey's prime minister says opposition parties have the right to file objections to the outcome of a recent referendum on expanding presidential powers, but warned that calling for street protests was unacceptable.
Binali Yildirim said Wednesday the electoral board would rule on the main opposition Republican People's Party's request for the referendum's annulment. Opposition parties have complained of a series of irregularities, particularly an electoral board decision to accept ballots without official stamps, as required by Turkish law.
Yildirim said the "the path to seek rights" should be limited to legal objections and urged the opposition to accept the vote's outcome.
Thousands have protested in Istanbul and Ankara since Sunday's referendum, which has set into motion the transformation of Turkey's system of government from a parliamentary into a presidential one.
This story has been automatically published from the Associated Press wire which uses US spellings