Samantha Lewthwaite, the so-called "White Widow", is reportedly training Isis (Islamic State) female suicide bombers in Syria.
The 30-year-old British terrorist, who is one of the world's most wanted women, is believed to have joined the Islamist militant group earlier this year to help with its terror campaign and instruct the group on how to exploit the media, according to The Daily Star.
Intelligence sources believe Lewthwaite has become one of the most powerful women in Isis's terror network, and is so well regarded that she is known as the "Special One" or the "Important Woman".
She is understood to be tasked with training and mentoring British and other white converts to Islam who have volunteered to fight for Isis.
"We have some very interesting signals intelligence which refers to a white British woman who holds a senior position in Islamic State," one source told The Daily Star.
"There has been mention of a woman joining IS after being married to a jihadi fighter who became a martyr, and there have been references to attacks in Africa.
"That narrows down the list of suspects. Other agencies have some human intelligence which also supports the theory that she is now in Syria."
It is believed Lewthwaite may also have assisted Islamic State in producing its graphic beheading videos which depicted the murders of American journalists James Foley and Steven Sotloff, as well as British aid worker David Haines.
"Her most powerful weapon is her use of propaganda – she may well be orchestrating the videos we have been seeing emerge from Islamic State in the last few weeks," the source said.
Lewthwaite is the widow of 7/7 bomber Germaine Lindsay and adopted the name 'Sherafiyah' when she converted to Islam.
She has spent more than two years on the run from British, US and Kenyan authorities for her role in plotting bomb attacks across Kenya in 2011.
Last month, a British police source said Lewthwaite is believed to have undergone plastic surgery in an attempt to evade capture.
Lewthwaite is heavily linked to Somalian terrorist group al-Shabaab, and is suspected of being involved in the group's attack on the Westgate shopping mall in Kenya's capital Nairobi last September, in which at least 67 people were killed.
"Islamic State have plenty of fighters but they lack someone who really understands how to exploit the Western media and this is where her strength is," the intelligence source added. "She is a female version of Joseph Goebbels. She is more use to them than a 100 volunteers and that is why she is so highly regarded within the organisation."
On Saturday, the UK sent two Tornado GR4 jets to Iraq and is now poised to commence air strikes against Isis targets after British MPs approved UK military action in the region by 524 votes to 43 at the House of Commons on Friday.