The memorial, designed by Peter Eisenman, opened in May 2005 and comprises 2,711 precast reinforced concrete blocks, which vary in height from ground level to 5m.
Cracks in the concrete began appearing at the end of 2005 and are now affecting 1,361 of the blocks.
According to a study published last month in German current affairs magazine Cicero, 40 per cent of the cracks were found to be bigger than 0.2mm.
A memorial foundation spokesman said: 'At the moment we cannot find the real reason for the cracks.
'But the experts assume that the cracks might be a result of the expansion and contraction that come with the temperature change.'
Repairs are scheduled to start in spring.
By Jessica Rowson (www.nce.co.uk)