Ofsted chief Sir Michael Wilshaw warned that the so-called "Trojan Horse" problem of extremist groups trying to take over the governing of the country's schools may not be over.
The scandal originated in Birmingham earlier this year and led to investigations across the UK.
Ofsted is set to conduct further inspections of schools and academies in January 2015.
"I don't think we've seen the end of the Trojan Horse issues," Sir Michael told the House of Commons public accounts committee.
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A letter sent to Birmingham Council had referred to an alleged Trojan Horse plot by hardline Muslims to seize control of a number of school governing boards in the city.
It sparked four separate investigations which resulted in at least five schools in the city being categorised as failing and placed into special measures.
Speaking to MPs, he said the department for education (DfE) had to make sure new leaders at the affected schools were doing a "good job".
The DfE said Ofsted was right to call for urgency, but added that there were a number of things that needed to be done that "unfortunately do take quite a bit of time, particularly around a variety of staffing changes".