The European Commission for Democracy through Law (Venice Commission) is concerned about the passing by the Ukrainian parliament of the law on national referendums that allows the changing of the country's constitution at a referendum.

"Many participants of today's meeting of the [Constitutional] Assembly expressed concerns about the new law on referendums, due to which the constitution could be amended at a referendum. The Venice Commission is also seriously concerned about the issue," Venice Commission Secretary Thomas Markert said in Kyiv on Thursday.

He added that the constitution should be approved by a majority of the parliament, while a referendum can be used as a supplementary stage of the procedure.

In turn, an adviser to the Ukrainian president, Maryna Stavniychuk, assured Markert that future amendments to the constitution would be approved only according to the procedure envisaged by the Constitution of Ukraine at the Verkhovna Rada, Ukraine's parliament.