“We confiscated files and computer data, which will now have to be analysed,” Hans-Jürgen Lendeckel, spokesman for the Hannover public prosecutor told the Bild am Sonntag weekly paper.
The authorities are investigating Olaf Glaeseker on suspicion of corruption in connection with event organiser Manfred Schmidt, a personal friend who organised a regular business lobby event, Nord-Süd Dialog. Glaeseker was Wulff's spokesman and advisor for years, particularly during his time as state premier of Lower Saxony.
Although Wulff sacked Glaeseker without explanation just a few days before Christmas, he had not cleared out his room in the Presidential Office building, just next to the presidential palace Bellevue in central Berlin – and it was raided on Thursday.
The Bild am Sonntag said Glaeseker had been refused entry to the building last weekend, but was now allowed in. His flat and another office in Lower Saxony were raided on January 19, as well as an office belonging to Schmidt.
The Lower Saxony state chancellery first said the state government had not been involved in the Nord-Süd-Dialog conferences, but details of such involvement have been emerging in the German media.
Wulff's reputation and support among the public is continuing to decline, and on Friday a state prosecutor ruled he could be called a liar, after a Green politician in Lower Saxony was reported for doing so.
Calls for the president to resign have continued, and Chancellor Angela Merkel has been repeatedly criticised for supporting him.
It is now more than six weeks since the start of the row over €500,000 Wulff, then Lower Saxony state premier, borrowed from the wife of a businessman friend and failed to publish. The businessman Egon Geerkens then accompanied Wulff on three official trips, it has been reported.
Wulff subsequently transferred the loan to a bank with which he had dealings, and made angry phone calls to newspaper editors about the publish the story.