A 12-year-old girl and a 13-year-old girl have been charged over an aggravated robbery of a Parap service station last week, NT Police said.

Police director of communications Mark Wilton said in a statement that about 10pm Friday two girls, aged 12 and 13, allegedly threw items at an employee at the United service station on the Stuart Highway in Parap, before stealing cash and cigarettes and running away.

He said both the girls were arrested a short time later and have since been charged with aggravated robbery, theft and criminal damage, and were bailed to appear in court at later dates.