Isolated communities and illegal Islamic schools are a "breeding ground" for terrorism, a senior police chief has said, as he warned the security services are investigating 600 extremist plots.

Neil Basu, the Metropolitan Police's counter-terror chief, said that the nature of the threat the UK faced has shifted, warning that the main danger came from extremists "in our midst".

Mr Basu highlighted the risk posed by illegal schools, saying: "segregated, isolated communities, unregulated education and home schooling are a breeding ground for extremist and future terrorists".

The Met's deputy assistant commissioner also revealed that the intelligence services were currently investigating 600 terror plots, of which 60 were opened in the past six weeks alone.

In July, Cressida Dick, the Met's commissioner, warned that 500 investigations were active.

Speaking during the Police Superintendents' Association conference yesterday, Mr Basu said counter-terror officers currently open more investigations than they close each week.

He added that there were also weaknesses in the country's borders and called for much stringent checks on arrivals as he warned the UK's terror threat level would remain at severe for at least the next five years.

He said: "It is not going to change. This was truly a summer like no other, it was truly a shift and not a spike, it is truly a new norm that we face."