Downing Street has defended the selection of campaigner Sara Khan to lead a new counter-extremism drive.
The Government confirmed on Wednesday that Ms Khan will head up the newly created Commission for Countering Extremism.
Ms Khan, whose official title will be lead commissioner, is co-founder of Inspire, a counter-extremism and human rights organisation.
Her website describes her as "one of the UK's leading Muslim female voices on countering Islamist extremism and promoting human rights".
However, she has been accused of being a "mouthpiece" for the Government by former Tory chairwoman Baroness Warsi, who described the move as "a deeply disturbing appointment".
She wrote on Twitter: "Sara is sadly seen by many as simply a creation of and mouthpiece for the Home Office."
The Muslim Council of Britain expressed "grave concerns" about the appointment.
Harun Khan, secretary general, said: "The fight against terrorism requires equal partnership between all parties, including Muslim communities.
"This appointment risks sending a clear and alarming message that the Government has no intention of doing so."
But a spokesman for Prime Minister Theresa May insisted Ms Khan is "expertly qualified" to lead the Commission's work and she will "bring a wealth of experience and knowledge to the commission."
Dame Louise Casey praised the "really important appointment" of Ms Khan.
The Government's former integration tsar told the Press Association: "She doesn't deny there is a problem...I think she has enormous courage, I think she is fiercely independent."
Discussing the appointment on Twitter, David Anderson QC, the former independent reviewer of terrorism legislation, said: "I for one will be giving Sara a fair chance, and wishing her the good luck that I suspect she will need!
"The idea that she is a Government stooge is hard to reconcile with her opposition (strongly shared by me) to its ill-advised 2015/16 plans for a Counter-Extremism Bill."
Plans to set up the commission were announced by Prime Minister Theresa May after the Manchester bombing in May last year - one of five terror attacks to hit Britain in 2017.
The body will be tasked with identifying and challenging all forms of extremism, advising ministers on new policies and promoting "pluralistic British values".
Its remit is also expected to include helping train schools and colleges to spot warning signs and ensuring women's rights are upheld.
Announcing the appointment, Home Secretary Amber Rudd said: "The Commission for Countering Extremism will form a crucial part of this Government's work to stop the scourge of extremism in all its forms and Sara Khan is expertly qualified to lead its important work.
"She will bring a wealth of experience and knowledge to the commission which will prove vital as it works to identify and challenge extremism and provide independent advice to the Government."
Ms Khan is expected to take her post in the next month.
The appointment is for a period of three years.