A report into allegations of bribery surrounding voting for the 2006 World Cup in Germany has found no wrongdoing, but investigators said the possibility that votes were bought cannot be ruled out because of the absence of key witnesses and documents.

Law firm Freshfields Bruckhaus Deringer was hired to carry out the investigation by the German Football Association (DFB) after allegations were made that money was paid to help secure rights to host the competition.

An excerpt of the 380-page report, released on Friday, states investigators "cannot prove that votes were bought, but we cannot rule this out either".

Former FIFA president Sepp Blatter and the organisation's ex-secretary general Jerome Valcke - both banned from all football activity - are among those Freshfields were unable to speak to while important documents could not be found.

Christian Duve from Freshfields told a news conference in Frankfurt: "We could not speak to all those with whom we wanted to talk."

The allegations originally surfaced in German publication Der Spiegel in October, with bid and organising committee president Franz Beckenbauer coming under fire.

The former Germany international denied votes were bought but acknowledged a "mistake" in accepting a FIFA subsidy from the organisation's finance commission.

Former DFB president Wolfgang Niersbach resigned from his position in November in the aftermath of the allegations, but also denied wrongdoing.

In a statement, FIFA said: "FIFA welcomes the report by the German Football Association (DFB) on its investigation into Germany's bid for the 2006 FIFA World Cup. FIFA will review the report carefully and factor the findings into its ongoing internal investigation of this matter.

"FIFA shared information with the DFB to assist with its investigation and, in turn, received information from the DFB that is helpful to FIFA's own investigation. However, many questions still remain to be answered.

"FIFA's investigation has been hampered by the fact that key witnesses were not willing to answer questions or provide documents.

"FIFA maintains its victim status in all investigations and continues to cooperate with the Swiss and German authorities, who are in the best position to obtain all of the information necessary to understanding the facts of this matter."