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.
The experts hope to wrap up the bulk of their work on the more than 1,500 pieces by the end of 2015.
Around 500 works found in 2012 in Gurlitt's flat in the southern city of Munich are suspected by the task force of having been plundered by the Nazis.
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 Swiss museum agreed late last month to accept the bequest and pledged to work closely with the task force to assist restitution efforts.
It has published a list of the artworks on its website
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".
The trove his son inherited has thrown a spotlight on the problem of looted art still held by museums and in private collections nearly 70 years after World War II.
Jewish groups strongly criticised the secrecy with which Germany initially handled the case and Berlin has been at pains to display more transparency on the issue.