Turkish police have detained a total of 38 people in İstanbul who took part in demonstrations in protest of a decision by the Turkey’s Supreme Board of Election (YSK) to consider unstamped ballots cast in a public referendum on Sunday valid.

The detainees, accused of making propaganda to question legitimacy of the referendum result, were reportedly taken to the İstanbul Police Office on Wednesday morning.

A constitutional reform package seeking to introduce an executive presidency in Turkey was approved by 51.4 percent of the voters in Sunday’s referendum.

During the voting, some citizens cast their votes in unstamped ballots while some citizens used envelopes and ballots they brought with them, which prompted some opposition parties and naysayers to raise suspicions about the votes’ validity.

In a statement on Monday morning, the YSK said the ballot papers and envelopes brought by some citizens from outside were produced by the YSK and they are authentic.

Demonstrations have been held across Turkey to protest the YSK decision to consider the unstamped ballots valid.

This article originally appeared in Turkish Minute on Apr 19.