The Labour Department says its inspectors found 17 shops around the country open on Sunday, in defiance of Easter trading laws.
The department says it is now considering whether to prosecute any of them.
Most retailers must close on Good Friday, Easter Sunday and for half of Anzac Day, but shops selling essential goods, such as dairies and those in tourist spots, can stay open.
Shops open illegally can be fined up to $1000 by the courts.
Twenty-two shops were found open on Good Friday.
Last year 19 shops were found open on Good Friday, and 19 on Easter Sunday.