Olaf Glaeseker is accused of corruption during his time as state government spokesman in Lower Saxony where Wulff was state premier from 2003 to 2010.
The 52-year-old allegedly helped party promoter Manfred Schmidt to find sponsors for a private economic summit called ‘Nord-Süd-Dialog’ from 2007 to 2009.
Glaeseker allegedly persuaded sponsors to cough up €650,000 for the meeting, using his position as leverage. Schmidt reportedly made €1 million profit from holding the summit in 2007, 2008 and 2009.
In return Glaeseker allegedly received nine free holidays in Spain and France as well as 19 plane tickets with a total value of around €12,000.
Glaeseker and Schmidt deny the corruption charges.
Wulff is expected to appear as a witness. His trial for accepting favours is ongoing.