A secret Government report has warned that more than 3,000 British children are being taken to Pakistan each year and enrolled in extremist summer schools.

The chilling Home Office study says courses at madrasas teach a 'glorified version of jihad', according to a source.

Officials fear some youngsters will be radicalised and return to the UK with a warped ideology and pose a terrorism risk.

'It is highly likely that this education in Pakistan, even for short periods of time, increases the risk of exposure to extremism for British-Pakistani children,' the source told The Mail on Sunday.

Denial: Students are seated at Pakistan’s Jamiatul Uloom Ul Islamia madrasa - the report identified this madrasa as among three of concern

'Enrolment at madrasas poses the greatest risk of exposure to more serious forms of religious extremism.'

Two of the 7/7 bombers, Mohammad Sidique Khan and Shehzad Tanweer, enrolled on madrasa courses in Pakistan a year before they launched their deadly attack in 2005, which killed 52.

But the security services have established that some Pakistani parents take their children back to their native homeland during summer holidays under the pretext of visiting extended family.

In reality, they sign them up for lessons at some of Pakistan's estimated 20,000 madrasas.

The report says some of those madrasas receive funds raised in Britain and that UK-based imams have established seminaries in their ancestral homeland.

It identifies three madrasas of concern – the Darul Uloom Haqqania (DUH) madrasa in the remote Khyber Pakhtunkhwa region bordering Afghanistan; the Jamia Binoria in Karachi and Jamiatul Uloom Ul Islamia in Azad Kashmir.

Each has denied involvement in extremism. The DUH madrasa has previously been labelled the 'University of Jihad' because former students include Asim Umar, an Al Qaeda leader, and it awarded an honorary doctorate to the former Taliban leader Mullah Omar.

There are also fears that British taxpayers may have inadvertently provided it with funds.

The Khyber Pakhtunkhwa government, which controversially handed a £2.2 million grant to the madrasa in 2016, will have received £283 million from Britain to help boost education when a ten-year project ends in 2020.

A satellite image shows a remote madrasa near Balakot, Khyber Pakhtunkhwa province, Pakistan

Denying any involvement with extremists, the madrasa's chief Maulana Hamid ul Haq said: 'If you ask questions about the 'Taliban', 'Taliban' is a term used for students so we call all students 'Taliban'.

If some of the students turn violent or extremist, then what can we do? We have nothing to do with it.'

The Jamia Binoria madrasa has been accused of adopting a 'pro-jihadi and anti-Western stance' and has reportedly enrolled foreign students. However, an official said British students no longer attended and the madrasa had no involvement in extremism.

The British founder of the Jamiatul Uloom Ul Islamia madrasa, based in Mirpur, also denied any links with terrorism. Haji Bostan, from Dewsbury, West Yorkshire, said no British students had enrolled and that no form of extremism was taught.

A Department for International Development spokesman said: 'All funds for Khyber Pakhtunkhwa are for agreed purposes. It does not include funding for madrasas.'