ANKARA (Reuters) - The deputy head of Turkey’s main secularist opposition called on Monday for the annulment of a referendum on boosting the powers of the president and said it would take its challenge to the European Court of Human Rights if necessary.

Bulent Tezcan, deputy chairman of the People’s Republican Party (CHP), said the party had received complaints from many regions that people had been unable to vote in privacy and said that some ballots were counted in secret.

He also said the High Electoral Board’s (YSK) decision to accept unstamped ballots was clearly against the law.

“At the moment it is impossible to determine how many such votes there are and how many were stamped later. This is why the only decision that will end debate about the legitimacy (of the vote) and ease the people’s legal concerns is the annulment of this election by the YSK,” Tezcan told a news conference.

He said the CHP would submit complaints to municipal election authorities and the YSK and, depending on the result of those appeals, would go to Turkey’s constitutional court, the European Human Court of Rights and any other relevant authority.