The structure of policing is partly to blame for the "exponential" growth of drugs networks, the head of the National Crime Agency has told MPs.

Lynne Owens said each of England and Wales's 43 forces was focused on running their local services rather than co-ordinating across borders.

She said progress on serious organised crime was moving at "glacial speed".

National Police Chiefs' Council head Sara Thornton said having fewer, bigger forces would make operational sense.

'County lines' gangs

Speaking at the Home Affairs Select Committee, Mrs Owens said police had not been able to make an impact on the drugs networks, which the Home Office believes are behind much of the increase in serious violence, because the priority of each force was to abide by a legal responsibility to run an "efficient and effective" local service.

The former Surrey chief constable said the new co-ordination centre, based at the NCA, was helping to disrupt some of the 1,000 "county lines" gangs, which use couriers - including children as young as 12 - to supply drugs from cities to smaller towns in rural and coastal areas.

"In the establishment of the county lines co-ordination centre we are now able to see where different police forces are working on the same telephone numbers unbeknown to one another because the intelligence and investment in digital data systems across the 43 forces is not in the place that it should be," Mrs Owens told the MPs.

Mrs Owens said there needed to be a national assessment centre to co-ordinate the fight against global, technologically enabled crimes, rather than individual approaches.

Ms Thornton agreed that the present set-up was unsatisfactory, saying forces had to "work around" the structure.

"If you did a poll of chief constables I think most would say for operational reasons it would make sense to have a fewer number of larger forces, but of course the issue isn't operational, it's political," she said.

Plans abandoned

A merger of Dorset and Devon and Cornwall Police remains under consideration after the chief constables and police and crime commissioners for the two forces put forward the proposals.

But since the last wholesale restructuring plans for the police service were abandoned in 2006, the Home Office has been unwilling to force through any changes without clear support on the ground.

The committee was also told that social media and internet companies must do more to tackle online threats, particularly cases of indecent images, referrals of which to the NCA had risen by 700% since 2013, Mrs Owens said.

"At the moment they take all of the profit, but they take minimal risk. And we think there are some big 'asks' of industry to prevent offences occurring in the first place," said Mrs Owens.

Cressida Dick, the Metropolitan Police Commissioner, said that cuts to the budgets of the police and other public sector services had contributed to the increase in serious violent crime alongside a "whole series" of social issues.

"I would be naive to suggest that reduced numbers of officers on the street... has had no impact. I'm sure it's had an impact together with a whole series of other things," she added.