LONDON (Reuters) - British Foreign Secretary Boris Johnson said on Monday he urged Iran to release detained dual nationals during a visit to the Islamic Republic.  I urged their release, on humanitarian grounds, where there is cause to do so,  Johnson told the British parliament.   These are complex cases involving individuals considered by Iran to be their own citizens, and I do not wish to raise false hopes. But my meetings in Tehran were worthwhile,  he said.  It is too early to be confident about the outcome.  Johnson said he raised with Foreign Minister Mohammad Javad Zarif  the official harassment of journalists working for BBC Persian and their families inside Iran.  
Britain urged Iran to release detained dual nationals: Johnson