The total number of coronavirus patients rose to 13,121 in the state, he said.
Three men, aged 56, 50 and 65, died of the coronavirus infection at a hospital in Ganjam, the worst-hit district in Odisha.
"Regret to inform of the demise of three COVID positive cases while under treatment in hospital," the official said.
The 56-year-old deceased was diabetic, while the 65-year-old man was suffering from diabetes and hypertension, he said.
Of the 64 deaths reported, Ganjam accounted for 39, while nine were reported from Khurda, six from Cuttack, two from Puri and one each from Angul, Bargarh, Bhadrak, Gajapati, Jajpur, Kendrapara, Rayagada and Sundergarh.
"Two COVID-19 patients, aged 50 and 57, also died but the causes of their deaths were head injury (polytrauma) and acute encephalomyelitis respectively," the official said.
The number of coronavirus patients who died of "non-COVID reasons" increased to 20, he said.
Of the new 595 cases, 394 were detected from quarantine centres across the state, while 201 were found through contact-tracing exercises.
The fresh cases were found in 21 different districts.
Ganjam reported the highest of 230 cases followed by Jajpur (97), Khurda (76), Koraput (44), Malkangiri (36), Gajapati (20) and Mayurbhanj (14).
Eleven cases each were reported from Balasore, Bhadrak and Cuttack, 10 from Puri, eight Sundargarh, five each from Jagatsinghpur and Nayagarh, four from Kalahandi, three each from Baragarh and Keonjhar, two each from Kendrapada, Sambalpur and Rayagada and one from Balangir.
Odisha now has 4,677 active cases, while 8,360 patients have recovered from the disease so far.
The state health department has so far conducted 3,34,527 tests, the official added. AAM BDC DV DV