A fifth of secondary schools believe gang culture is widespread among their pupils, while many more report teenagers carrying weapons and drugs, Ofsted has said.

About 40 per cent of schools reported pupils bringing weapons into the playground or classroom at least once a term, Ofsted said.

Inspectors found about half of schools thought "gang behaviour" among feuding groups of pupils was a recurring issue, with 20 per cent describing the problem as widespread.

In a new report on tackling disruptive behaviour, Ofsted stressed that there was a lack of hard evidence to back up the perception of a widespread gang culture.

But the report said drug abuse was "a daily challenge" for some older teenagers.

"In most secondary schools, there are drug-related incidents at least once a term," it said.

Chief inspector of schools David Bell highlighted the growing discipline problems facing English schools in his annual report last month.

Both Labour and the Tories have promised tough action to combat disruptive behaviour in schools ahead of the next General Election.

Inspectors visited 78 institutions to gather evidence for the latest report, including 15 secondary schools.

The report said: "In one in five of the secondary schools visited, gang culture is perceived to be widespread, although few schools had firm evidence of it.

"There were instances of the carrying of knives and other potential weapons reported in less than half of the secondary schools and pupil referral units (where expelled pupils are taught) and in about half of the colleges visited."

Mr Bell added: "Although the large majority of schools are orderly places where children behave well, it is worrying that unsatisfactory behaviour has not reduced over time."