The executive head of the leading Holocaust restitution organisation, the Claims Conference, defended its record when he faced some of its critics in London on Monday.

Greg Schneider, executive vice-president of the New York-based body, addressed an audience of 150, including many survivors, at the invitation of the Anglo-Jewish Association, one of four British groups on its board.

Recent controversy has focused on two particular issues: grants given to education rather than the welfare of Holocaust survivors, and compensation for Jewish properties in East Germany seized by the Nazis.

After 1992, properties where no heir was found passed into the hands of the Claims Conference, which uses the proceeds for home care for Holocaust survivors and Holocaust education.

But last year an independent report by QC Jeffrey Gruder, commissioned by the Board of Deputies, criticised the Conference for not doing enough to help potential heirs locate their assets and called on it to republish a list of properties. Challenging Mr Schneider, Martin Stern, a longstanding critic, said: "It is not your money. You are holding 5,000 properties belonging to Jews of German origin".

But Mr Schneider disputed the figure, and said that the Conference had repeatedly extended the deadline for potential heirs to make a claim.

On education grants, he said, there had been "heated" internal debate within the Conference but that they amounted to just £11.5 million a year.

Survivor Hermann Hirschberger – due to receive his MBE yesterday for helping former refugees with compensation claims – took issue with money going to education.

"Who gave you permission?" he said. "Was not your most important and sacred duty to pay it to the survivors and people who suffered?"

But Auschwitz survivor Freddy Knoller supported the allocations. "The greatest fear we have is that the Holocaust might be forgotten when we are not available any more to speak in schools," he said. "Education must be continued."

After a meeting with Greg Schneider, Board vice-president Paul Edlin said: "We are encouraged by what we have heard, Greg and his colleagues are now listening to the points we have raised and will seek to address them."