The surprise followup operation started Monday evening and finished at 2.30am yesterday.
During the search, 52 smart phones, more than 100grammes of crystal methamphetamine, and 50gm of raw opium were found.
The followup search was conducted alongside urine tests, which showed at least 655 inmates had abused drugs.
Nakhon Si Thammarat police chief Maj General Ronnapong Saikaeo said yesterday many of the smart phones found in the followup search were brandnew.
He said it was clear these devices had been delivered to many inmates right after the surprise search on Sunday.
The surprise operation on Sunday had uncovered about 300 cell phones, some illicit drugs, and many weapons.
"Some prison officials have clearly supported drug traffickers who operated their network behind bars," Ronnapong complained yesterday.
He urged the Corrections Department to take action against these corrupt officials as well as inmates who had benefited from mutual ties with them.
Ronnapong said many inmates have used the ties to claim their status as wellbehaved prisoners - allowing them to stay on the list for a royal pardon.
Ronnapong said these corrupt officials should be fired and face legal prosecution.
He said after Sunday's surprise search at the Nakhon Si Thammarat Central Prison, many drugtrafficking operations in the South were disrupted.
"Clearly, they cannot arrange the delivery of illicit drugs and manage the financial transactions because the bigtime traffickers have lost their cell phones," Ronnapong pointed out.
Up to 14 officials at the Nakhon Si Thammarat Prison have now been barred from entering the inmate zones because of their suspected role in giving the banned items to inmates who can afford them.
An informed source said these 14 officials were now under huge stress.
Corrections Department directorgeneral Suchart Wongananchai yesterday vowed to take tough action against the guilty officials.
"If found guilty, they will be fired. They will face criminal proceedings and their assets will be seized too," he said.
Speaking on condition of anonymity, an operationlevel official at the Nakhon Si Thammarat Central Prison said some of his colleagues had taken considerable amounts of money from inmates for a long time.
"One official has bought a rubber plantation of more than 200 rai," he said. "Another has just bought a brandnew Fortuner vehicle".
The official lamented that with the corrupt network, more than 90 per cent of inmates at the prison had not been reformed into good persons.
"On the contrary, they have learned to excel in the criminal world here," the same official said, "Here, they will know where to get drugs and where to sell them in a larger volume".