Their disappearance underscores the lack of protection afforded Sudan's rich but under-developed archaeological heritage.
"They are small statues, about 10-15cm high but it's very significant because the Napatan kingdom is one of the important periods in Sudanese history", Abdurrahman Ali, head of the country's museums, told media outlets.
He said the statues, dating from 450 BCE (Before Common Era), disappeared from a small museum at the Jebel Barkal heritage area in northern Sudan.
The loss was not discovered for three days, he said.
A reporter who visited the museum recently found it protected by one guard at the gate. Artifacts, including many small statues, were held in a poorly-lit room. Some were displayed openly on tables.
Pyramids and other ancient sites are also poorly guarded and receive relatively few visitors in Sudan's remote desert.
Officials last month announced that the Gulf state of Qatar is giving $135m to support Sudanese archaeology over five years.
Part of that money will go towards protecting the sites.