Ankara is considering a package of 26 proposals to amend a constitution drafted under the military authority that followed a coup in 1980. The amendments to the Turkish Constitution would change the structure of the court system by moving the power from the military and into the hands of the president and prime minister, both from the ruling Justice and Development Party, or AKP.
A group of Turkish activists in a letter to the European Commission said the proposed reforms fell short of expectations. They complained members of the AKP weren't taking their critics seriously.
Angela Filote, a spokeswoman for the EU Enlargement Commission, told Turkish newspaper Hurriyet that the EU "fully supported" the letter.
The letter to European leaders goes on to complain that their criticism of the measure is being viewed as support for military rule and stands in the way of Turkey's efforts to join the EU.
"As a result, it has become impossible to hold a rational debate on the process," the letter reads.
Turkey votes on the referendum Sunday.