Pierre van Hooijdonk says former club Celtic could win the Champions League if they were part of a British league.
The notion of a league incorporating Rangers and Celtic with English sides was raised again this week by Celtic majority shareholder Dermot Desmond.
Dutchman Van Hooijdonk, 45, played as a striker for Celtic from 1995 to 1997 before joining Nottingham Forest.
"I hope that it happens," he said. "Celtic is a club capable of taking it to another level."
Van Hooijdonk, who played 46 times for the Netherlands and scored 14 international goals, believes the sheer size of the Celtic fan-base would mean the club would be able to compete with the top English sides and propel them to success in Europe.
"They will grow if they have the chance to join a British league," he explained.
"I'm sure if they had the opportunity to join the Championship tomorrow, they would do it.
"And then in five years I am positive they would be challenging for the title in the Premier League just because of the fact they are able to grow and the money that comes from the television is so much they can spend it on the right players.
"If you are challenging for the Premier League title, when you have the system where you have the four teams competing in the Champions League then they have a really good chance.
"I certainly do believe - and I said it already in the days I was playing here - if they have the opportunity to join the English league without a doubt they are going to be one of the main forces in the league."
Now a players' agent, Van Hooijdonk was in Glasgow this week to watch Celtic draw with another of his former clubs, Fenerbahce, in the Europa League.
And, asked if Celtic could win the Champions League if they were part of a British set-up, the Dutchman replied: "Yes, because of the fact they get more money. That is the most important thing. With the fan-base behind it, it's going to be crazy."