A former Warsaw town hall official, his parents and a lawyer are among five people taken into custody over irregularities in real estate restitution, Poland's chief prosecutor's office said Monday.

An investigation into restitution decisions in Warsaw was ordered last year following media reports that, in violation of the law, city officials had given ownership of a valuable downtown plot of land to people unrelated to its original owners.

The decision was part of a wide process of restitution of real estate that was seized under communism from its pre-World War II owners. The process has been long known to be breeding irregularities, with lawyers and businessmen specializing in acquiring rights to houses and plots and then selling them at huge profit.

Chief Prosecutor Zbigniew Ziobro's office said the five will be questioned as suspects. A separate state-run Central Anti-Corruption Office said the allegations include corruption.

"In the past such perpetrators could sleep peacefully while ordinary people, illegally evicted from their homes, suffered," Ziobro's office quoted him as saying.

"But now the prosecutors are taking steps to make them take the responsibility for their criminal actions."

Poland is one of very few former communist countries that have no formal process for returning or compensating people for real estate seized, or "nationalized," under communism following World War II. A number of draft restitution laws were knocked down by politicians, who argued that Poland could not afford an across-the-board solution.

As a result, highly valuable property has been returned to people who, in many cases, have no connection to it. The new owners often raise the rent, cut utilities and bully the tenants out of homes they lived in and took care of for decades. They then sell the refurbished apartments for hefty sums, making fortunes.