The Foreign Secretary arrived in Tehran yesterday and held “frank” discussions with foreign minister Javad Narif, during efforts to free the mother-of-one, who has been imprisoned since April last year.
Mrs Zaghari-Ratcliffe is serving a five-year sentence over allegations that she was plotting to overthrow the Islamic government.
The Anglo-Iranian was arrested during a holiday visit to her parents.
Reports suggest she could appear in court again on Sunday, following threats to increase her sentence by five years following Mr Johnson’s gaffe of telling a parliamentary committee that she had been in Iran to train journalists.
He later acknowledged this was not so. Because Iranian authorities do not recognise her British citizenship, they have refused her access to British consular officials.
Her husband, Richard Ratcliffe, declined an offer to accompany Mr Johnson after receiving advice that it may not help his chances of visiting his wife in future.
When the couple lastspoke by telephone on Tuesday, Mrs Zaghari-Ratcliffe was “genuinely worried about the court case and getting quite agitated”, he said.