Part two PROCEEDINGS IN GENERAL
II. PROCEEDINGS IN CRIMINAL CASES
Chapter 24 Detention and arrest
Section 9
When a person is apprehended or arrested or when an order for arrest under Section 8, first paragraph is executed, he shall be informed of the offence for which he is suspected and the grounds for his arrest. Immediate relatives or other persons particularly close to him shall also be notified of the arrest as soon as it can be done without causing harm to the investigation. However, such notice may not be given against the wishes of the arrested person without extraordinary reason. (SFS 1998:24)
Rights during investigation - informed of belief that crime has been committed
EDIT.