ZAGREB, Croatia (AP) — A far-right group campaigning for a change in Croatian election laws said Thursday it has collected enough signatures to call a nationwide referendum that could curb significantly the rights of ethnic minorities.

The "People Decide" group said it has collected nearly 400,000 signatures for a vote on a proposal to reduce the number of lawmakers in Croatia's parliament from 150 to a maximum 120, curb the number of MPs representing ethnic minorities and ban them from voting on crucial issues such as forming Croatia's government and the national budget.

"Today we are celebrating the festival of democracy," Zvonimir Troskot, the group's coordinator, said before announcing the number of signatures, which should automatically lead to a referendum. Parliament may, however, decide to submit to the Constitutional Court a request to review the proposed referendum questions.

Prime Minister Andrej Plenkovic said any such referendum would be unconstitutional and that it should be verified whether the signatures were collected within a legal time period.

The group also seeks to redraw Croatia's vote constituencies in a way that would apparently give far-right groups better chances of securing seats in future elections.

The potential referendum has triggered criticism from rights groups and left-leaning parties, which say that restricting the rights of minority lawmakers would be against the constitution and the basic principles of parliamentary democracy.

Serbs are the largest minority in Croatia, the European Union's newest member, where far-right groups have steadily gained ground in recent years.

Copyright 2018 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.