The double attack occurred late Thursday when two separate car bombs went off in the parking lots of the Cristal, formerly Sheraton, and Babil hotels.
Initial reports said 10 people were killed and 27 wounded, but the casualty figures rose overnight.
All officials spoke on condition of anonymity because they are not authorised to speak to the media.
Nobody claimed responsibility, but Iraq witnesses almost daily attacks that have been frequently claimed by the Islamic State group which seized large swaths of the country during a blitz last year.