The 58-year-old convict had to be admitted to the national hospital in Colombo where doctors later retrieved the handset from his rectum.
"The man had concealed the phone inside his person," the official said, asking not to be named.
"Unfortunately for him, the phone rang at the wrong time and guards knew he had a phone at the wrong end."
He said the man was in hospital for two days but was discharged and sent back to prison Friday after the mobile phone was taken out.
The prisoner is serving a 10-year term for theft at the high security Welikada jail in the capital..