In a post on his official Twitter account, Bozdag said the report proves that the Venice Commission of Council of Europe was "siding with No voters" in the April 16 referendum.

"The report is not fair, objective, unbiased and technical, but completely political and subjective," Bozdag said, adding that it lacked value for Turkey.

A delegation from the Venice Commission of Council of Europe visited Turkey last month to speak with Turkish officials about the plans for constitution amendments that would give wide-ranging executive powers to the president.

"Venice Commission or any other international organization will never influence the free will of the Turkish people," Bozdag wrote Tuesday.

"Anyone who takes the Venice Commission report as a reference cannot have a correct opinion about the constitutional amendments in Turkey," Bozdag said.

The Venice Commission comprises of constitutional experts and advises the Council of Europe, of which Turkey is a member.

The constitutional changes have been discussed since Recep Tayyip Erdogan was voted president in August 2014. The 18-article bill was passed by parliament in January, with 339 votes in favor -- nine more than needed to put the proposal to a referendum.