Foreign Secretary Jack Straw says he is worried about some of Pakistan's Islamic schools, reportedly visited by one of the London bombers.
Children at a madrassa
Shehzad Tanweer, according to his uncle, went to one of the schools in December wanting to learn to recite the Koran by heart.
Mr Straw said the Pakistan government was also concerned about some of the schools, called madrassas.
He said Pakistan was increasingly cooperating on counter-terrorism.
The International Crisis Group recently said the Pakistan government had "allowed religious organisations, jihadi groups and the madrassas that provide them with an endless stream of recruits to flourish".
It suggests 10-15% of the madrassas are radical.
Foreign Secretary Jack Straw told reporters Pakistan faced a big challenge to improve madrassas.
"We are concerned about what goes on in some, though not all, of the madrassas in Pakistan but so too is President Musharraf and many, many people in the Pakistan political parties and Pakistan government," he said.
Message to British youths
Mr Straw said there was a major reform programme in Pakistan to provide secular education alongside the religious schools.
And he said there was "intensive and increasingly substantial co-operation" between the UK and Pakistan on counter-terrorism.
He refused to reveal details of any contacts with Pakistan officials over the London bombings investigation.
Labour MP Mohammed Sarwar told BBC News the madrassas provided young people living in "abject poverty" in Pakistan with food and clothes, as well as religious education.
It was therefore convenient for parents to send children to the schools.
"We have to deal with this problem and we should ensure that in madrassas they are in state control," he said.
"Secondly, it is very important that science education and education for other things should be an essential part of those madrassas."