The ACT government estimated more than $5 million had been spent in businesses since the scheme launched on June 9.

More than $4 million of that was spent between Friday and Saturday.

"Customers had to spend at least double the amount of a voucher in order to use it, this injection into the economy is a combination of ChooseCBR funding and customers' own spending," a government spokeswoman said.

The $2 million limit for the ChooseCBR vouchers was spent in 24 hours after it opened on Friday morning.

Canberrans have expressed frustration that they weren't able to use their allocated vouchers over the weekend, while questions have been raised over which businesses claimed the most vouchers.

The ACT government has refused to provide that detail, saying it was a privacy issue.

Opposition business spokeswoman Leanne Castley said an audit of the scheme was needed to "give the community the answers they are looking for".

"Concerns have been raised with me about the misuse of vouchers and the inequitable distribution of funds," Ms Castley said.

"It's a real kick in the guts for small businesses who put in upwards of 15 hours' work to be eligible for each of the iterations of ChooseCBR, only to receive $20 or $50 in total benefit."

"I welcome any measure that assists Canberra businesses. However, this scheme has been plagued with problems from the beginning and caused undue stress on business owners, staff and customers.

Ms Castley called on the ACT government to be "upfront and transparent" about where and how vouchers were redeemed.

Almost 60,000 vouchers were redeemed by 30,000 customers although the government said it was possible people may have registered multiple times.

The government spokeswoman said customers could access up to three vouchers per day and use one per store.

A different phone number is needed for each registration.

"It is possible that individuals could have registered more than once if they were able to access more than one mobile phone number, but we are unable to verify this," she said.

READ MORE:

An ACT government spokeswoman earlier said the most popular businesses in the scheme couldn't be named but included food retailers, cafes and restaurants.

"We are unable to provide information on individual businesses. However, it is important to note that many businesses have been busy," she said.

Our journalists work hard to provide local, up-to-date news to the community. This is how you can continue to access our trusted content: