The request appears to have been made as part of the condition to lend material to the Cycladic exhibition due to be mounted by Karlsruhe from December 2011 (details).
Harald Siebenmorgen, the director of the museum, is reported to have rejected the Greek request.
Siebenmorgen said they were purchased with public funds in 1975 and Greece had no legal claim to them, because of the moratorium on civil claims and Germany had not signed a convention on restitution of art treasures until 1992.
Siebenmorgen told SWR 2 television that a linkage between restitution claims and loans was 'not the international custom at all' and said it was 'like extortion.'
This raises several issues. The acquisitions were made after 1970, and Siebenmorgen will be aware that major North American museums have complied with Italian requests for the return of material that was acquired post 1970 (even though the USA had not become a signatory at that date). What is the full collecting history of the two disputed pieces? Is there good reason to believe that they were looted from archaeological sites in Greece?
Greece has been asked to loan archaeological material to an exhibition and its officials have every right to expect the highest ethical standards from the museum organising the Cycladic show.
Research by Gill and Chippindale has demonstrated the significant impact of looting on the archaeological record of the Cyclades, highlighted, in part, by an earlier exhibition of Cycladic material in Karlsruhe. I would have expected Siebenmorgen to have adopted a more positive and conciliatory approach to the Greek request.