Germany's Football Association (DFB) will hold an emergency meeting on Monday following the shock resignation of a referee under suspicion of fixing at least one Cup match and betting on the result.
Referee Robert Hoyzer, who according to the DFB has denied the allegations, is suspected of betting on the first round German Cup tie between first division Hamburg SV and regional league side SC Paderborn last August.
DFB joint-president Theo Zwanziger said on Sunday that there was also evidence of manipulation of other games involving the 25-year-old Hoyzer, who resigned on Friday.
"Since Friday we have had evidence that he rigged games," Zwanziger said on German television station ARD.
The match at the centre of the allegations is Hamburg's Cup defeat by Paderborn on August 21, 2004.
Hamburg took a 2-0 lead but went on to lose 4-2 after Hoyzer sent off striker Emile Mpenza in the first half for insulting him and awarded two penalties to the regional league side.
Germany was rocked by a massive corruption scandal in 1971, with sanctions eventually imposed on 53 players, two coaches, six officials and the clubs Arminia Bielefeld and Kickers Offenbach.
The current scandal threatens to overshadow the announcement on Monday of ticket sales procedures for the 2006
The DFB called an emergency meeting on Monday and said they would look to complete their investigation as soon as possible.
"It is always the obligation of the board of control to reach their conclusions swiftly, particularly in so stressful a case," board president Horst Hilpert told German sports news agency SID on Sunday.
DFB spokesman Harald Stenger added: "We will leave no stone unturned in this investigation."
Hamburg SV said they would consider legal action if their suspicions were confirmed.
"Great damage has been inflicted on Hamburg SV and on German football," Hamburg's club chief Bernd Hoffman told ZDF television. "We will use all legal means to put right this wrong."
The DFB has already ruled out any possibility of replaying the match.
Hamburg were bottom of the Bundesliga at the time after losing their first two games. Coach Klaus Toppmoeller went on to lose his job in mid-October.
"I had the impression at the time that this was a match we could never win," Toppmoeller told ZDF.