LONDON: New charges of "propaganda against the system" made by Iran against British-Iranian national Nazanin Zaghari-Ratcliffe, a week after she finished serving a five-year sentence, are "unacceptable", Britain said Sunday.

"It is unacceptable that Iran has chosen to continue a second wholly arbitrary case against Nazanin Zaghari-Ratcliffe," Foreign Secretary Dominic Raab wrote on Twitter.

"She must be allowed to return to her family in the UK without delay. We continue to do all we can to support her," he added.