Katrice Lee from Hartlepool was two when she vanished in 1981.
Her parents have always claimed that military police were slow to react to their daughter's disappearance.
Her father, Richard, says that although he welcomes the apology, he feels a public inquiry is the only way he will discover the truth.
More top news
A look ahead at the forecast for the Tyne Tees region
Northumbria police force is facing allegations of fostering a culture of "sexism" by a former employee.
A thief who stole his dying sister's life savings and left her children with no inheritance has walked free from court.