Ambrusics, 19, is in his third season at the Walkers Stadium, where he has come through the academy set-up.
This is the Hungarian's first season as a professional and he was on the bench for Leicester's Carling Cup win at Leeds earlier in the season.
"Robert is somebody Gerry (Taggart) and I know well from our days at Leicester and we want to give him a chance here at Boundary Park," said Latics manager Paul Dickov.
Source: PA
Source: PA