ANKARA - Turkey supports Syria's national unity and unilateral moves such as declaring a federation cannot be valid, a foreign ministry official told Reuters, amid expectations that Syrian Kurds will announce a federal system in northern Syria on Wednesday.The Turkish official said the form of government and administrative structure of Syria will be decided by all sections of the Syrian people with a new constitution.Idris Nassan, an official from Kobani, one of three autonomous areas set up by Kurdish groups two years ago, said earlier that Kurdish-controlled areas of northern Syria were expected to declare a federal system on Wednesday.