O'Neill: Old Firm should join Premier League
"I think Celtic and Rangers joining would enhance the Premier League and make us all strive to get better," O'Neill told Aston Villa's television channel AVTV on Wednesday.
O'Neill managed Celtic from 2000-05 winning three Scottish League titles and three Scottish FA Cups.
"It was spoken about a few seasons ago and obstacles were put in the way. The idea died at that time and I don't know how strong the possibility is at the moment," he added. "I certainly support the idea. But, then again, I could be a voice in the wilderness."
The idea of the two Old Firm rivals playing in England has periodically been mooted for decades and the debate was re-kindled two weeks ago when Bolton Wanderers chairman Phil Gartside outlined his plans for a two-division Premier League which included Celtic and Rangers.
UEFA, European football's governing body, has strict rules on clubs competing in different national leagues and are likely to oppose any such move while the Scottish League are also historically opposed to the idea.