An associate of football match-fixing suspect Tan Seet Eng has been detained at a Milan airport following a tip-off by Singapore authorities to Italian police.
Admir Sulic arrived at Milan's Malpensa Airport from Singapore on a 6am flight and was detained by police.
The suspected associate, who is not a Singapore national, was arriving on a flight from Singapore and would be detained at Milan airport.
A joint inquiry by Europol, the European anti-crime agency, and national prosecutors has identified about 680 suspicious matches, including qualifying games for the World Cup and European Championships, and for Europe's Champions League.
Italian prosecutors have accused Mr Tan, also known as Dan Tan, of heading an organisation to fix football matches worldwide and Italian police have issued an arrest warrant for him.
Interpol has declined to say if it has declared the Singapore national to be an internationally wanted person.
However, an Italian judicial source said Interpol had pooled together investigations launched by authorities in various countries, including Italy, Germany, Spain and Turkey.
Singapore says he is not wanted there, but that it is working with European authorities investigating the syndicate.
Singapore police said last week it was sending officers to Interpol to assist in the investigation and that the city-state remained "highly committed" in the fight against match-fixing.
The Interpol investigation has shone a spotlight on what experts say is rampant match-fixing in Asia, where lax regulation combined with a huge betting market have made football a prime target for crime syndicates.
Last year, the head of an anti-corruption watchdog estimated that $1 trillion was gambled on sport each year or $3 billion a day, with most coming from Asia and wagered on football matches.