The money was needed after costs increased due to "delays through the pandemic" said Birmingham City Council's leader Councillor Ian Ward.
It came as he moved to reassure colleagues that the Commonwealth Games were still on track to take place in 2022.
Councillor Ward revealed the city council has had to draw on “contingency funding” to cover extra costs of the preparation works due to the pandemic but stated this had come from within its allocated budget.
It reportedly committed £185.6m to the games out of a total cost of £778m, and papers put to the city council’s cabinet in February suggested an extra £15m may be required.
Councillor Ward confirmed contingency funding has been drawn on to cover extra costs of the redevelopment of the Alexander Stadium in Perry Barr as well as the £73m Smethwick Aquatic Centre.
Speaking at a council scrutiny committee, Councillor Ward said: “We are still planning to deliver the games and deliver a fantastic event in the summer of 2022.
“There’s not been any drastic change to plans to deliver the games.
“[…] Some contingency funding has been used within the allocated budget for the stadium and the aquatic centre. That’s due obviously to increased costs caused by delays through the pandemic.”
It is unclear at this stage how much extra funding has been put into the project to build the aquatic centre, on the site of the former Londonderry playing fields off Londonderry Lane.
He added: “I take the view now that the games are even more important to Birmingham and the wider region than they were previously.
“Coming out of this there is going to be a real need to stimulate the economy and I do think that the games is now critical to that for Birmingham and the wider region and it’s fantastic that we’ve got the opportunity, actually, to use the games to provide that stimulus for the economy.
“The alternative, of course, would have been that we are sat here watching another city make preparations and plans for the 2022 Commonwealth Games so we have got to keep going – we are determined to deliver a fantastic event that will be at the heart of a year of celebration for the whole nation in 2022.
“I do believe that Birmingham will be at the very heart of that celebration. This is a fantastic opportunity for the city and we need to make the most of it.”
Councillor Ward touched on the scheduling of sporting events in 2022, which has changed in light of the Olympics being pushed back due to the coronavirus crisis.
He said: “There have been talks with other sports organisers about the sporting calendar for the summer of 2022 because that sporting calendar is now very, very crowded.
“The world championships in swimming [World Aquatics Championships] and the world championships in athletics [World Athletics Championships] have been pushed back 12 months in a domino effect because of the Olympic Games going back 12 months.
“Both of those championships were due to be in 2021 and are now moving back to early summer of 2022.
“There are ongoing discussions with the organisers of the women’s European football championships [UEFA Women’s Euro] to see if we can make these events run as smoothly as possible through the summer.
“There are also discussions going on with the BBC who are televising a number of these events.
“There will no doubt when these discussions are concluded be something said by the OC [Commonwealth Games Organising Committee] about how all of this is going to work, but I’m not aware of any discussions around social distancing for these events.
“We do need to remain optimistic – hopefully by the time we get to 2022 this whole situation may well be beyond us.
“Let’s hope that science does win out and there is some form of vaccine or mitigation that means we can return our lives to normal.”