"It is unacceptable and unjustifiable that Iran has chosen to continue with this second, wholly arbitrary, case against Nazanin Zaghari-Ratcliffe. The Iranian government has deliberately put her through a cruel and inhumane ordeal. Nazanin must be allowed to return to her family in the UK without further delay," Raab said in a statement.
The foreign secretary said London would "continue to do all we can" to support Zaghari-Ratcliffe.
Zaghari-Ratcliffe was released from five-year custody in Iran on espionage charges last Sunday but prohibited from leaving the country in order to stand before court on a new set of charges. The trial on propaganda charges began earlier today in a Tehran court.
Zaghari-Ratcliffe, a Thomson Reuters Foundation employee at the time, was arrested in Iran in April 2016 on suspicion of plotting against the Iranian government. Sentenced to five years behind bars, she was released from prison and put under house arrest last March on COVID-19 grounds.