Georgia's penitentiary service has dismissed the claims and says Saakashvili’s health is "satisfactory".
Georgia's former president Mikheil Saakashvili is in need of urgent hospital treatment during his hunger strike, his doctor has said.
Medical professionals say Saakashvili's condition is deteriorating ten days into the protest.
"His condition has worsened, he has difficulty walking, it is difficult for him to speak," Dr Nikoloz Kipshidze told Georgian TV on Sunday.
Kipshidze added he would seek Saakashvili's transfer to hospital from the prison where he is being held near the capital Tbilisi.
But Georgia's penitentiary service said in a statement the claims were untrue and the former president's condition was "satisfactory".
"Mikheil Saakashvili is taking prescribed medications," the authority said. "As a hunger striker, he is constantly monitored by medical staff."
The 53-year-old has refused to eat since he was arrested on his return to the country on October 1.
Saakashvili faces several charges in Georgia and was sentenced in absentia in 2018 to up to six years in prison for abuse of power.
He left Georgia in 2014 but returnED this month to try and galvanise opposition ahead of municipal elections.
The United National Movement party that was founded by Saakashvili came a distant second to the ruling Georgian Dream party in the election that was held two days after Saakashvili’s arrest, although mayoral races in the country’s six largest cities will be decided in a second round of voting.