LONDON - World tennis' anti-corruption unit says it received alerts of unusual or suspicious betting on 48 matches between January and March, including one at the Australian Open.

The Tennis Integrity Union says one alert involved a WTA Tour match, but other matches were from lower-ranking tournaments.

The TIU did not name any of the matches or players involved.

There were 31 alerts in the same opening quarter for 2015.

The TIU says an alert should not be seen as definite evidence of match-fixing, adding that factors like "player fitness, fatigue and form" can also explain unexpected activity.

It says "the total of 48 alerts received during the quarter should be seen in the context of the 24,110 matches played around the world in that period, representing a tiny percentage of 0.2."