Loew, who led the Germans to their fourth World Cup title in 2014 in Brazil, said he had full trust in DFB President Niersbach.
"You can rely 100 percent on his word," Loew said in a statement. "We could not have wished for a better president. I am certain the open questions will be answered. I know that this is what Wolfgang Niersbach wants."
German magazine Der Spiegel reported on Friday that Germany's bid committee for the 2006 World Cup had tapped into a slush fund of 6.7 million euros (5 million pound) back in 2000 to buy votes at world soccer's governing body FIFA.
It said the alleged slush fund had been set up with 6.7 million euros loaned by the late Adidas CEO Robert Louis-Dreyfus for Germany's World Cup bid committee to pay bribes to FIFA officials in order to help land the tournament for Germany.
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Der Spiegel reported those aware of the alleged slush fund had included Franz Beckenbauer, head of the 2006 organising committee, and Niersbach, who was a vice president of the committee.
"I find it unfair how undifferentiated part of the coverage in the past days has been and what conclusions were drawn without having any proof," said Loew, who was an assistant coach when Germany finished third in the 2006 World Cup.
"I have seen the DFB for the past 11 years as a seriously led federation," Loew said. "President Wolfgang Niersbach, for whom I have great trust, represents exactly that."
Niersbach, Beckenbauer and the DFB have vehemently rejected the allegations as "groundless" and have said the magazine had provided no evidence to back up its claims.
Frankfurt's state prosecutor launched an initial "monitoring process" on Monday, a procedure that will determine whether a formal investigation into the affair is needed.
The DFB has said its own investigation had found no wrongdoing in the 2006 World Cup process, but was investigating a payment of 6.7 million euros ($7.6 million) from the committee to FIFA for a cultural programme and whether it was used as intended.
(Reporting by Karolos Grohmann, editing by Ed Osmond)
