Recep Tayyip Erdogan
Recep Tayyip ErdoganReuters

Turkey's election authority on Wednesday rejected opposition requests to cancel the referendum held this week that boosted President Recep Tayyip Erdogan's authority, AFP reports.

The narrow victory of the 'Yes' campaign in Sunday's referendum handed Erdogan sweeping new powers, most of which will come into force after 2019, but was disputed by his rivals.

The main opposition Republican People's Party (CHP) and the pro-Kurdish Peoples' Democratic Party (HDP) had on Tuesday asked that the poll be scrapped over alleged violations, according to AFP.

Although the 'Yes' camp won with 51.41 percent, it was a narrower-than-expected victory with the opposition claiming the outcome would have been reversed in a fair poll.

However, ten members of the Supreme Election Board (YSK) decided against annulling the vote, while only one voted in favor, the board said in a statement.

The constitutional reform was first introduced in late 2015. Critics of the reform say it would essentially turn Turkey into a dictatorship. Erdogan’s supporters reject this notion.

Bulent Tezcan, CHP deputy leader, told CNN Turk the YSK's decision to reject the petitions sparked a "serious legitimacy crisis".

Meanwhile, there have been daily street protests in anti-Erdogan neighborhoods in Istanbul since Sunday's referendum, with thousands chanting slogans and banging pots and pans in an angry show of discontent.

Istanbul police on Wednesday detained 16 leftist activists involved in demonstrations, according to AFP.

Speaking in Ankara, Turkish Prime Minister Binali Yildirim said the matter of the election result was closed and warned against further protests.

"Turkey is a state of law... and there can be no talk of anarchy, activities in the street," he said, adding, "I call on people not to give in to provocations or get caught up in incitement."