Federbet is looking into claims that a large number of bets were placed overseas by Asian syndicates around half an hour into the first leg.
At that point, the score was still 0-0, although the Dons were well on top and their rivals had a number of players in the book.
Federbet general secretary Francesco Baranga said: "Before the match, the odds were around 9/10 for more than three goals and we noticed that a number of bets were being placed on the outcome.
"This was normal, as Aberdeen were obviously big favourites to win.
"But, after 27 minutes, it was still goalless and the odds collapsed to 1/5. The bets were coming in from the Asian markets, where it's known for agencies to contact players in eastern Europe."
It is still believed that Aberdeen are not under suspicion and are going through the usual preparations for Thursday's away leg.
A Dons spokesman said: "All we are doing is concentrating on reaching the next round."
The SFA is monitoring the situation, and will await the findings of any investigations and discuss them with Sportradar, who monitor betting patterns on the governing body's behalf.
Source: STV