A Polish commission reviewing restitution of property seized by the state after World War II canceled two decisions returning plots of land in Warsaw to private hands on Monday.

It was the first decision by the panel led by the populist government's deputy justice minister, Patryk Jaki. The commission was established in June in response to a public outcry over irregularities revealed in the restitution process.

The decision means that Warsaw authorities will not hand over two plots to the private claimant, who is not related to the prewar Jewish owners or to their one known heiress. Against public protests, a renowned high school was moved from a building on one of the plots in preparation for the restitution.

Jaki said that was "against public interest and incurred unnecessary costs."

The panel is expected to review more cases in the coming weeks.

Communist authorities seized the highly valuable plots and buildings from Polish, Jewish and other owners in Warsaw and in some other cities through post-war decrees. The ouster of communism in 1989 has made restitution of the property possible.

Poland is among the last central and east European countries that have not returned seized property. It neither has a law to regulate the process. Individual claims are made to courts which then order the city authorities to return the property. But the process has led to irregularities.

Jaki said that Mayor Hanna Gronkiewicz-Waltz failed to verify the validity of the restitution claim in the case.

Some observers say the commission is being used as a tool against opposition figures, including Warsaw's mayor who refused to appear before the panel, and including former prime minister, Donald Tusk, who is now head of the European Council.

Some city officials, lawyers and businessmen have been arrested as part of a separate criminal investigation on suspicion of helping in and profiting from the irregular restitutions and will be brought before the panel.