An art historian claims to have found two art works stolen by the Nazis insideGermany's parliament, in a new embarrassment for authorities after a huge stash of looted art came to light last month.

Bild newspaper said the two works were an oil painting, Chancellor Buelow speaking in the Reichstag, by Georg Waltenberger dated 1905, and a chalk lithography entitled Street in Koenigsberg by Lovis Corinth.

The Nazis plundered hundreds of thousands of art works from museums and individuals across Europe. An unknown number of works is still missing and museums around the world have conducted investigations into the origins of their exhibits.

The Bundestag, in a statement issued after the report in Bild, said an art historian was reviewing two "suspicious cases", but a spokesman would not confirm the find. The art historian's investigations into the German parliament's art collection, which began in 2012, were continuing, the Bundestag spokesman said.

Last month German authorities revealed that a trove of Nazi-looted art, valued at €1 billion, had been found in a Munich apartment.

That collection had been held for decades by Cornelius Gurlitt, the elderly son of an art dealer of part-Jewish descent who was ordered by Hitler to buy up so-called "degenerate art" and sell it to raise funds for the Nazis. Bild said one of the two works discovered in the Bundestag collection had also originally belonged to the Gurlitt family.

German authorities have been criticised for keeping quiet for two years about the discovery of Mr Gurlitt's trove of 1,406 European art works which included works by Picasso and Matisse.

Mr Gurlitt has demanded his art back, and lawyers working on reclaiming property for heirs to Jewish collectors say he may get to keep at least some of the works.

The Bundestag's art collection comprises around 4,000 works and Bild said investigations had found some 108 pieces so far of unknown provenance. Four years ago it returned a portrait after it was found to have been stolen by the Nazis.

The Central Council of Jews in Germany called for a list of the Bundestag's art works to be published.

"If the Bundestag is keeping lists of its collection secret, hindering the press in its investigations, protecting the perpetrators of Ayranisation and not informing the heirs, I would wish those responsible to show more sensibility and tact," said Dieter Graumann, president of the Council.