Concerns over Lincolnshire Police child protection
Lincolnshire Police needs to improve the way it protects vulnerable children, government inspectors have found.
A report by the police watchdog said most child protection teams were not fully staffed.
Officers also needed to be "swifter to pursue people suspected of downloading and distributing indecent images of children".
Lincolnshire Police said it had restructured its protection teams.
Her Majesty's Inspectorate of Constabulary and Fire and Rescue Services (HMICFRS) carried out its inspection in September.
Details of 81 cases of children at risk were examined.
Inspectors found the force's child protection practice as good in nine cases, as requiring improvement in 47 cases, and inadequate in 25 cases.
The HMICFRS said that Lincolnshire also needed to focus on "driving down their backlog of visits to registered sex offenders".
HM Inspector of Constabulary Zoë Billingham said inspectors were "impressed by the clear undertaking made by senior leaders to improve the way it manages risks to children", but the force had "more work to do".
"As a result of our inspection, we've asked the force to draw up an action plan to address our concerns," she said.
"We plan on revisiting Lincolnshire later this year to see what progress has been made."
Ch Supt Steve Taylor said he was confident the inspectors would "see we have made significant improvements at their next visit".
He said the number trained child protection officers had increased by 30%.
He added: "Other areas we have been focusing on include making sure that visits to sex offenders are robustly managed which now has a dedicated detective inspector overseeing, and that cases concerning indecent images are investigated at the very earliest opportunity."