US president says ‘important sources’ also told him executions not going ahead as Iranian airspace reopens to flights after near-five-hour closure

US president says he ‘may have to act’ before talks amid crackdown that rights group says has led to at least 538 deaths

US president says ‘help is on its way’, as reported death toll rises into the thousands and concerns Tehran may carry out first protest-related execution, that of Erfan Soltani