Celtic warned they would have to sell Odsonne Edouard for £40m amid Leicester transfer interest
Leicester have been linked with a summer move for the French striker, who scored a hat-trick in Celtic's 5-1 Scottish Premiership opening-day win over Hamilton on Sunday.
Foxes boss Brendan Rodgers brought Edouard to Glasgow on loan from Paris Saint-Germain in 2017, before signing him permanently for a club-record £10m fee a year later.
Brattbakk, who played for Celtic between 1997 and 2000, insists a £40m offer for the 22-year-old would be too good to turn down amid the coronavirus pandemic.
He told the Mail : "I think it would be really tough to say no to a bid of that amount. It's so much money.
"Financially, Celtic is still doing well. But any club would appreciate £40m right now.
"Also, if you sell him for that kind of money, you could buy one or two new players for maybe £10m and you'd still be left with £30m.
"This is always the discussion that you have. The club will always think about ten-in-a-row but also about how best to run it.
"If you ask the supporters, of course, they'd all give Edouard a better contract to stay on.
"But it's not that easy. The board of directors have to think about both things which makes it difficult."
Since his arrival at Celtic Park, Edouard has scored an impressive 65 goals in 127 appearances.
And Brattbakk thinks Edouard's valuation could rise if he continues scoring goals before the new Premier League season starts on September 12.
He added: "He won't be sold this week and if he plays well next week and scores a couple of more goals, there will definitely be more interest in him.
LATEST FOOTBALL NEWS
Arsenal news: Three-year deal for Willian, Lacazette for Partey, new deals for duo
Man United news live: Sancho deal close, Gomes signs for Lille, starlet's new deal
Benzema teases boxing move at end of football career due to Mike Tyson admiration
Sir Rod Stewart calls into talkSPORT and defends Rangers after shock claim
Rangers sign ex-Leeds ace, Thiago wouldn't be in Liverpool XI, Ole quizzed on Sancho
Wigan lose 12-point deduction appeal, EFL confirms
Angel Gomes pens emotional message to Man United fans as new club is confirmed
Man United transfer would be 'dream come true' for Leicester's Kasper Schmeichel
Bundesliga clubs outline conditions for fans to return as early as September
Liverpool news live: Sancho family reveal Reds interest, Sarr talks, latest on Thiago
"The English league doesn't start until September 12. If Edouard plays well in the next four or five games and adds to his number of goals, the bids could even rise to £55m or £60m.
"It's a good situation for Celtic at the moment. The SPFL has started, the EPL hasn't and there are plenty of games for him to show himself to other clubs.
"If Leicester bid £40m, maybe another club will come in with more."
Former Celtic striker Harald Brattbakk believes the Hoops should cash in on Odsonne Edouard if they receive a £40million bid.