“This could be about corruption, fraud or breach of trust,” Frankfurt chief prosecutor Nadja Niesen told SID sports news agency, an AFP subsidiary.
“We will examine the available documents. But we are still at the very beginning and have not yet launched an investigation. This could happen if we can confirm there is initial cause for suspicion.”
Germany won the right to host the 2006 World Cup by beating South Africa with 12 votes to 11 after New Zealand's Charles Dempsey abstained in the final ballot.
On Friday, Der Spiegel weekly published a report claiming that the German Football Association (DFB) had a slush fund to buy votes.
The magazine claims the DFB borrowed 10.3 million Swiss francs in 2000 from the now-deceased former CEO of German sportswear giant Adidas, Robert Louis-Dreyfus, in order to buy the votes of four Asian members of FIFA's 24-strong executive committee.
Spiegel claimed the DFB then transferred €6.7 million – the equivalent of the borrowed Swiss francs at the time – to a FIFA account in 2005 to repay Louis-Dreyfus.
The DFB preempted Spiegel's claims by issuing its own statement admitting they had made that last payment to FIFA but denying it had any connection to the 2006 World Cup.
“There was no slush fund,” DFB president Wolfgang Niersbach insisted. “The World Cup was not bought.”
Niersbach added that the internal investigation had not been completed but said: “I can definitively exclude that this payment was linked to the World Cup.”
On Sunday, Franz Beckenbauer, who led Germany's successful bid to host the 2006 World Cup, came out to deny the allegations.
“I have not sent anyone money to acquire votes for the awarding of the 2006 World Cup to Germany,” said the 70-year-old football legend in a statement.
“And I'm sure that no other member of the bidding committee did either.”
This is the latest body blow to hit world football's governing body ahead of the emergency meeting of FIFA's executive committee in Zurich on Tuesday.
FIFA has suspended president Sepp Blatter for 90 days due to suspicions a two million Swiss franc (€1.8 million) payment he made to UEFA counterpart Michel Platini was not above board.
Alongside Blatter, Platini and FIFA's secretary general Jerome Valcke have also been suspended for the same period by the governing body's independent ethics committee.
Swiss investigators are also looking into the awarding of the 2018 World Cup to Russia and the 2022 tournament to Qatar in a bribery scandal which has seen 14 people arrested by American and Swiss authorities.
Seven former FIFA officials were arrested by Swiss authorities in May as the United States attempts to have them extradited to face charges of accepting bribes.