A police spokeswoman has said no arrests had been made at the Jameah Islamiyah Secondary School in Mark Cross, Sussex, after police carried out searches early today.
The spokeswoman said police officers started their operation at the site at about 6am, and searches were taking place.
She added: “No arrests have been made. The people in the school have been very co-operative.”
She could not speculate on how long the searches would carry on for.
Media organisations were later driven by police about 300 yards down a country lane to the outside of the school.
A lone officer stood guard outside its black steel gates, and more officers were posted at different points along the pathway leading to its main entrance.
Set within 54 acres of East Sussex countryside, the Jameah Islamiyah Secondary School is housed in the dilapidated Victorian-style buildings of a former convent.
It opened in September 2003 as an independent day school for Muslim boys aged 11 to 16, with annual fees of £1,000 (€1,500).
According to its last (UK education authority) Ofsted report last year, the school in Mark Cross, near Crowborough, had only nine boys on its roll, aged from 12 to 15.
The school said in a statement to inspectors that it aimed to “provide a high standard of academic and Islamic education” and to “develop real Islamic morals“.
Its vast grounds are often used at weekends as a retreat for Muslim families living in London wanting to escape the city.
However, Ofsted inspectors found the school failed to provide a satisfactory education for its pupils, and has significant weaknesses.
In addition, although the pupils are well behaved and self-disciplined, the school does not provide a safe environment in which learning can take place, inspectors noted.
Last weekend it emerged that hate preacher Abu Hamza booked a weekend for himself and his followers at the school after seeing an advert for the retreat in a London mosque.
The school’s imam Bilal Patel said he was immediately concerned about Hamza’s strange behaviour, and how intimidating the sight of Hamza and his 15 followers must have looked to neighbours.
One local, who declined to be named, said: “There have been rumours about the school being used to teach young Muslims extremism for some time.
“I’m not sure how the rumours came about, but the school does nothing to integrate in the community. You rarely see any of the pupils or people associated with the school in the village. It seems to want to keep what it does away from the outside world.”
Another villager, Philip Child, 18, who lives about 300 yards from the school, said: “A while ago, the school was run as a quiet place but recently I’ve got the sense that they are doing more to get involved in the community.
“They have become more chatty, and sometimes if they need advice to fix one of their cars or something, they would come round.
“It’s a shock to think that something like this could be going on round here, but at the moment we just don’t know what’s going on.”