A prison that holds nearly 600 foreign national inmates has been warned not to be complacent about "worrying signs" of an increasing drugs problem.
Inspectors said Maidstone Prison was "calm and well-ordered" but a 14.5% positive rate in random drugs tests was "too high to be taken lightly".
Just after the inspection 15 parcels of smuggled items, including drugs, were thrown over the wall in a single night.
HM Prison Service said measures had been implemented to tackle the issue.
Incidents at the jail were was mostly low level, inspectors said.
'Old and shabby'
About 40% of prisoners at the Category C men's jail - which was last inspected in August 2015 - are under the age of 30.
Inspectors found generally good relationships between staff and prisoners, but Chief Inspector of Prisons Peter Clarke said he needed to "sound a note of caution" about the impact of illicit drugs at the jail.
The 14.5% positive rate in random drugs tests was recorded in October.
Mr Clarke's report said the night "some 15 parcels containing contraband, including drugs, were thrown over the wall into the prison" highlighted that "the response to intelligence was poor with backlogs and suspicion searches were not being carried out in a timely fashion or at all".
"There was clearly a need to refocus on the strategy for reducing the supply of illicit drugs, and there is certainly no room at all for complacency," he said.
Other findings by inspectors included "old and shabby" residential accommodation in need of refurbishment, and a decline "in terms of the purposeful activity" available to prisoners, with far too much of the work available being "mundane and menial".
"I was surprised to see large numbers of prisoners in workshops playing games rather than being engaged in work," he said.
Chief executive of HM Prison and Probation Service, Michael Spurr, said: "The governor and staff have worked hard to address the needs of the foreign national prisoners they hold, and Maidstone is providing a consistent regime to support effective resettlement while enhancing its provision of education and employment opportunities.
"We note the concerns raised about the impact of drugs and a number of measures have already been implemented in recognition of this emerging issue.
"Working with police and the local authority we have increased perimeter security, incoming mail is now scanned for illicit substances, while searches and drug tests are being undertaken more frequently.
"The early indications are that these measures are having a positive impact."