The former Celtic and Scotland player was one of three men arrested as part of the operation, with the 32-year-old confirming that police officers came to his home in South Lanarkshire at 7am on 1 December, before taking him to the London Road police station in Glasgow.
Confirming he was not arrested, Griffiths denied any wrongdoing, and declined to discuss the subject of the questioning.
The police have issued a statement on the situation, saying: “Following a pre-planned police operation on Thursday, December 1, three men aged 37, 35 and 32 were arrested in the Bothwell, Bonnyrigg and Airdrie areas in connection with an investigation into alleged gambling incidents in sport.
“All three men were released without charge pending further enquiries.”
Griffiths spent eight years at Celtic from 2014 to 2022, winning seven league titles and three Scottish Cups during that period. He has also made 22 appearances for the Scotland national team.
The 32-year-old has, however, been without a club since October, having spent a brief time playing in Australia. He has been training with Scottish club Livingston, for whom he made his professional debut in 2006 at the age of 16.
Last month, the Football Association (FA) charged Brentford striker Ivan Toney over 232 alleged breaches of betting rules, with the bets having taken place between February 2017 and January 2021.
FA rules state that betting on football is banned for all players, managers, coaches, club staff, directors and licensed agents involved in the Premier League.