The head of the panel of experts, Ingeborg Berggreen-Merkel, said there had been a strong response to its call for the families of suspected victims of art looting under Hitler to come forward and stake claims.
"We are reviewing each individual case -- the people have a right to that," she told German news agency DPA.
But she added: "Thoroughness must in each case trump speed."
The 14-member international task force was established a year ago to sort through the spectacular trove hidden for decades by Cornelius Gurlitt, son of a powerful art dealer during the Third Reich.
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Berggreen-Merkel said the panel had focused first on claims by Holocaust survivors, then on queries from descendants.
"We want to give people whose families suffered so terribly under these appalling conditions answers as soon as possible," she said.
Gurlitt died in May and named in his will the Museum of Fine Arts in Bern as the sole heir of the more than 1,000 paintings and sketches by Picasso, Monet, Chagall and other masters.
The Bern museum has said the approximately 500 dubious pieces would stay in Germany and not "pass through its doors" until thorough provenance research had been completed.
Gurlitt's father Hildebrand was tasked with selling works taken or bought under duress from Jewish families, and avant-garde art seized from German museums that the Hitler regime deemed "degenerate".