Germany's Football Association (DFB) widened its investigation into suspected match-rigging to look at five more games on Monday, while a local public prosecutor's office launched its own probe into the scandal.
German referee Robert Hoyzer, who has denied allegations of match-fixing, is suspected by the DFB of rigging a Cup match he took charge of last August after betting on the result.
The DFB held a five-hour meeting on Monday as an issue, which has shocked German football, threatened to overshadow the announcement of ticket sales procedures for the 2006 World Cup, which Germany is hosting.
After the hastily convened meeting, the DFB said they had further suspicions over two second division matches and three regional league matches.
Four of the five games were refereed by the 25-year-old Hoyzer, who has never taken charge of a first division game.
The DFB, who said they would hear from further witnesses in the case this week, confirmed that the public prosecutor's office in Braunschweig had started an investigation into the allegations.
They also raised the possibility of banning players, coaches, officials and referees from betting on matches and pledged to set up a commission to examine ways to prevent similar problems arising in the future.
"In the interest of the credibility of German football, we will do everything to clear up this case and we are therefore making all known facts available to the public prosecution service," DFB co-president Theo Zwanziger said.
Hoyzer, who resigned from the DFB on Friday, flatly denied having bet on any match he had taken charge of.
"I have never bet on a game I have refereed," he told Germany's Bild newspaper on Monday.
"The accusations have left me pensive, uneasy and dismayed. I cannot comprehend them, and also cannot understand that my refereeing colleagues could think me capable of such a thing."
The match at the centre of the original allegation is the defeat of first division Hamburg SV by SC Paderborn in the German Cup 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.
Hamburg launched a formal appeal against the result on Monday, despite the DFB stating that replaying the match would be impossible. The German Cup is now at the quarter-final stage.
The two second division matches identified by the DFB were the games between Rot-Weiss Essen and FC Cologne and Ahlen versus Wacker Burghausen.
The regional league games between SC Paderborn and Chemnitzer FC, Eintracht Braunschweig and FC St Pauli and Wuppertaler SV versus Werder Bremen Amateurs will also be investigated.
The match between Rot-Weiss Essen and Cologne was refereed by another official, who is not under suspicion, but the DFB said Hoyzer was still suspected of manipulating the match.
Germany was rocked by a corruption scandal in 1971, with sanctions imposed on 53 players, two coaches, six officials and clubs Arminia Bielefeld and Kickers Offenbach.
(Additional reporting by Alexandra Hudson in Berlin)