British IS recruiter Sally-Anne Jones was reportedly killed in a drone strike in Syria in June.
Jones, who had no previous military training, joined the so-called Islamic Sate after travelling to Syria in 2013.
The BBC’s security correspondent Frank Gardner said Jones had been a useful propaganda agent for the group on social media and her death would be “significant”.
Her death was first reported by The Sun.
Jones, from Chatham in Kent, had been used to recruit Western girls to the group and posted threatening messages to Christians in the UK.
She married the jihadist computer hacker Junaid Husain, who was killed in a drone strike in 2015.