ANKARA, April 17 (Xinhua) -- The legitimacy of Turkey's referendum on an executive presidency is open to debate, the head of Turkish main opposition Republican People's Party (CHP) said on Sunday, as he criticized the High Electoral Board for making the vote "controversial."

Turkish main opposition Republican People's Party (CHP) Kemal Kilicdaroglu said those who advocated a "Yes" vote in the referendum may have gone beyond the boundaries of the law, private broadcaster NTV reported.

Earlier on Sunday, the CHP deputy leader Erdal Aksunger said it will object to the referendum results on grounds that the vote for the constitutional amendment were manipulated in terms of content and method.

The party reportedly would demand a recount of up to 60 percent of the votes.

Unofficial results showed a narrow 51.4 percent lead in the referendum for constitutional amendments that will change governing system from parliamentary system to presidential one.