Israel’s official Holocaust memorial, Yad Vashem, has condemned the installation of new plaques in Poland at the site of the Jedwabne pogrom, during which hundreds of Jews were burned alive in World War Two.

It says that the inscriptions – which were installed as part of a crowdfunded alternative memorial and not by any official body – “falsify history” by trying to absolve Poles of blame for the massacre.

On Wednesday, Gazeta Wyborcza, a leading Polish newspaper, reported that seven large boulders had been placed near the official Jedwabne memorial.

The objects had appeared there shortly before today’s commemoration of the 84th anniversary of the pogrom, which occurred when Poland was under Nazi-German occupation.

Official findings by Poland’s state Institute of National Remembrance (IPN) have established that the direct perpetrators of the massacre were ethnic Poles who lived in the area. But it also noted that broader responsibility for the crime rested with the German occupiers.

However, many in Poland – in particular on the political right – question those findings, arguing that the pogrom was entirely the work of the Germans and claiming that the tragedy has been used as part of efforts to falsely shift blame onto Poles for Holocaust crimes.

One of the newly installed plaques reads, in Polish and English, that “evidence and witness accounts disprove the claims of Polish perpetration of the murder of Jews in Jedwabne…In reality, this crime was committed by a German unit”.

Another says that the fact Poland disappeared from the map of Europe for 123 years between 1795 and 1918 was “an unimaginable tragedy for Poles…[but] a source of satisfaction for many Jews”.

A further one says that, in the interwar period, “many Jews openly sympathised with communism, identified with the Soviets, who were hostile to Poland”, reports Gazeta Wyborcza.

The newspaper notes that Wojciech Sumliński – an author who has written books questioning the official findings regarding Jedwabne – spoke two years ago about installing such plaques as part of an alternative “monument” that would recognise the “truth” about Jedwabne.

Sumliński himself confirmed on Wednesday in a social media post that he was behind the new installation, which was paid for through a crowdfunding campaign. On Thursday, he and a large crowd of supporters gathered for the official opening of the new memorial, marking the occasion with a Catholic mass.

On Thursday, Yad Vashem issued a statement saying that it is “profoundly shocked and deeply concerned by the desecration of historical truth and memory at the Jedwabne memorial site in Poland”.

It says that the new plaques are “an apparent attempt to distort the story of the massacre of Jews” in order to “absolve the perpetrators” through the “blatant falsification of history”.

“Yad Vashem calls on the relevant Polish authorities to remove this offensive installation and to ensure that the historical meaning of the site is preserved and respected,” they wrote.

The new plaques were also condemned by Poland’s chief rabbi, Michael Schudrich, who told Gazeta Wyborcza they are a “disgrace” and a “manifestation of the disease that is antisemitism”.