Prague  - The Czech Republic's Constitutional Court is to hold its first hearing on a challenge to the European Union's reform Lisbon Treaty on October 27, a court official said Tuesday.

To come into force, the treaty requires the signature of Czech President Vaclav Klaus, who is not allowed to ratify it until the court rules on the challenge.

The complaint was lodged by 17 Klaus supporters in the parliament's upper house, the Senate, on September 29.

According to the daily Lidove Noviny, the anti-Lisbon senators plan to file additions to their challenge. Their intention is not to influence the hearing's date, the court's general secretary, Tomas Langasek, said.

He said that it was impossible to predict when the court would issue its verdict in the case.

The Lisbon Treaty, which aims to boost EU's global standing by reforming its institutions, requires ratification by all 27 EU members to come into force.

In a last-minute condition for his signature, the Czech president wants his country to get an exemption from the treaty's Charter of Fundamental Rights, which he views as a threat to Czech citizens's property rights.(dpa)