BEIRUT (Reuters) - A top aide to President Bashar al-Assad said on Friday the Syrian government would fight any force, including U.S.-backed forces also battling Islamic State militants, in its drive to recapture the whole of the country.

Assad has previously vowed to recapture the whole of Syria. The government controls the main urban centres in the west of the country and has taken back much of the eastern desert from Islamic State in recent months.

"Whether it's the Syrian Democratic Forces, or Daesh (Islamic State) or any illegitimate foreign force in the country ... we will fight and work against them so our land is freed completely from any aggressor," Bouthaina Shaaban said in an interview with Hezbollah's Al Manar TV.

Shaaban said the U.S.-backed Syrian Democratic Forces (SDF) had captured areas from Islamic State "without any fighting", apparently accusing them of collusion with the jihadists.

The SDF "are trying to get areas (where there is) oil ... but they will not get what they want," she said.

Shaaban also said plans to "divide" Syria had failed, without elaborating.

The Kurdish YPG militia, which dominates the SDF, has for years controlled large parts of northeastern Syria.

Advances against Islamic State in its Raqqa stronghold and a new offensive in Deir al-Zor are bringing more territory under the control of the SDF.

(Reporting by John Davison; Editing by Gareth Jones)