A Syrian Democratic Forces (SDF) female fighter stands with her weapon east of Raqqa city, Syria. REUTERS/Rodi Said

BEIRUT (Reuters) - The northern Syrian city of Raqqa is expected to join a decentralized system of government being set up by Syrian Kurdish groups and their allies once it is freed from Islamic State, a leading Kurdish politician told Reuters on Monday.

Raqqa, Islamic State’s main urban base of operations in Syria, is the focus of an ongoing campaign by the U.S.-backed Syrian Democratic Forces (SDF), an alliance of Arab and Kurdish fighters that is closing in on the city.

The main Syrian Kurdish militia, the YPG, already controls swathes of northern Syria, where Kurdish groups and their allies are working to establish a decentralized system of government in areas captured from Islamic State.

The political project is causing deep alarm in Turkey, which sees the YPG and its political affiliate, the PYD, as an extension of Kurdish groups that are fighting an insurgency on Turkish soil.

Saleh Muslim, the co-chair of the Syrian Kurdish PYD party, said it would be up to the people of Raqqa to decide their future once the city is freed from Islamic State, but he thinks the city will join the “democratic federal” system.

“We expect (this) because our project is for all Syria ... and Raqqa can be part of it,” Muslim said in a telephone interview. “Our only concern is that the people of Raqqa are the ones who take the decision on everything.”

The “democratic federal” system aims to build on three autonomous areas set up by the main Kurdish groups in the north. The blueprint for the new system of government was approved by a constituent assembly in December.

Muslim added that Raqqa needed to be in “friendly hands” otherwise it would form a “danger to all Syria, particularly northern Syria, the federal system of northern Syria, the areas of self administration”.