Before the hearing, Jiri Oberfalzer, one of the senators, said the group was not planning another complaint if the court ruled against them.

"We really do not have any other complaint in our pockets," he told Czech television.

"We tried to exhaust every point that remained in the treaty as disputable, so we are preparing nothing else."

Property rights

Czech ratification also hinges on a demand by Vaclav Klaus, the country's president, for his country to obtain an opt-out from a rights charter attached to the treaty because of concerns over property rights in the Czech Republic.

Some Czechs are worried that ethnic Germans - 2.5 million of whom were expelled from Czechoslovakia after the second world war - may try to claim back their property.

EU leaders are expected to discuss Klaus's demand at a summit in Brussels later this week.

Miroslav Lajcak, Slovakia's foreign minister, said on Monday that his country will also insist on a similar opt-out to the one demanded by Klaus.

The last-minute demand was issued by Slovakia at EU talks in Luxembourg.

Lajcak said his country, a successor state to the now defunct Czechoslovakia, would need the same opt-out because they share the same law that expelled the ethnic Germans.