Seven European club matches, including one Champions League qualifier, are under investigation after last week's exposure of a match-fixing ring, UEFA said on Wednesday.
"From the original list of around 40 fixtures in Europe that were considered suspicious in terms of results, UEFA is further investigating seven European club competition fixtures under its jurisdiction in more detail," said UEFA general secretary Gianni Infantino in a statement.
"The five clubs involved are KF Tirana (Albania), FC Dinaburg (Latvia), KS Vllaznia (Albania), NK IB Ljubljana (Slovenia) and Budapest Honved (Hungary).
German police said on Friday that they had dismantled a gang with more than 200 suspected members operating in nine European leagues.
Wednesday's announcement came after a meeting with the nine national associations who were named by police as having domestic matches under investigation.
The matches were played in July and August this year; one in the Champions League second qualifying round, four in the Europa League second qualifying round and two in the Europa League third qualifying round.
"Irrespective of the above matches, UEFA is today also opening its own investigation into the possible involvement of three referees and one other individual connected to UEFA, in the match fixing," added the statement.
"Contrary to media reports, there is no suspicion or investigation into any UEFA administration staff.
"UEFA wishes to stress that it has been cooperating fully with the German police and authorities on the case and indeed, following a request from the German police for information on a number of matches, UEFA was able to assist thanks to its betting fraud detection system.
"UEFA will file criminal complaints, together with the relevant national associations, as soon as possible against clubs, officials and/or players in those countries concerned.
1. Stabaek IF v KF Tirana (July 21, Champions League second qualifying round
2. Bnei Yehuda Tel Aviv v FC Dinaburg (July 16, Europa League second qualifying round)
3. FC Dinaburg v Bnei Yehuda Tel Aviv (July 23, Europa League second qualifying round)
4. KS Vllaznia v Rapid Vienna (July 23, Europa League second qualifying round)
5. Rapid Vienna v KS Vllaznia (July 16, Europa League second qualifying round)
6 .NH IK Ljubljana v Metalurg Donetsk (Aug 6, Europa League third qualifying round)
7. Fenerbahce v Honved (July 30, Europa League third qualifying round)